Anne Eskild

• Haavaldsen, Marit Camilla; Thomas, Owen Matthew Truscott & Eskild, Anne (2026). Risk of pre-eclampsia according to gestational age across three decades: population-based study. Ultrasound in Obstetrics and Gynecology. ISSN 0960-7692. 67(2), s. 155–161. doi: 10.1002/uog.70160. Fulltekst i vitenarkiv
• Sagberg, Karianne; Lie, Torgrim; Peterson, Helene Fjeldvik; Hillestad, Vigdis; Eskild, Anne & Bø, Lars Eirik (2025). A new method for placental volume measurements using tracked 2D ultrasound and automatic image segmentation. MITAT. Minimally invasive therapy & allied technologies. ISSN 1364-5706. 34(3), s. 230–238. doi: 10.1080/13645706.2025.2449699. Fulltekst i vitenarkiv Vis sammendrag

  Background: Placental volume measurements can potentially identify high-risk pregnancies. We aimed to develop and validate a new method for placental volume measurements using tracked 2D ultrasound and automatic image segmentation. Methods: We included 43 pregnancies at gestational week 27 and acquired placental images using a 2D ultrasound probe with position tracking, and trained a convolutional neural network (CNN) for automatic image segmentation. The automatically segmented 2D images were combined with tracking data to calculate placental volume. For 15 of the included pregnancies, placental volume was also estimated based on MRI examinations, 3D ultrasound and manually segmented 2D ultrasound images. The ultrasound methods were compared to MRI (gold standard). Results: The CNN demonstrated good performance in automatic image segmentation (F1-score 0.84). The correlation with MRI-based placental volume was similar for tracked 2D ultrasound using automatically segmented images (absolute agreement intraclass correlation coefficient [ICC] 0.58, 95% CI 0.13–0.84) and manually segmented images (ICC 0.59, 95% CI 0.13–0.84). The 3D ultrasound method showed lower ICC (0.35, 95% CI −0.11 to 0.74) than the methods based on tracked 2D ultrasound. Conclusions: Tracked 2D ultrasound with automatic image segmentation is a promising new method for placental volume measurements and has potential for further improvement.

• Kulseng, Carl Petter Skaar; Sommerfelt, Silje; Flo, Kari; Gjesdal, Kjell Inge; Peterson, Helene Fjeldvik & Hillestad, Vigdis [Vis alle 8 forfattere av denne artikkelen] (2025). The association of placental to fetal ratio with pregnancy duration. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 104(5), s. 913–921. doi: 10.1111/aogs.15082. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Our objective was to study the association of placental size, fetal size, and placental size relative to fetal size (placental to fetal ratio) at gestational week 27 with time to spontaneous delivery. Material and Methods We included 100 pregnancies in a follow-up study from gestational week 27 until spontaneous delivery. Placental and fetal volume (in cm3) were measured at gestational week 27 by magnetic resonance imaging (MRI), and the association of placental to fetal ratio (placental volume/fetal volume) with delivery after spontaneous onset of labor was estimated as hazard ratios (HR) by applying Cox regression models. Pregnancies with deliveries after planned cesarean section or induction of labor provided follow-up time until these events. An HR lower than 1.0 indicates decreased risk of spontaneous delivery. Results Mean placental volume was 532 cm3 (SD 136 cm3) at gestational week 27, and fetal volume was 961 cm3 (SD 112 cm3). This yielded a mean placental to fetal ratio of 0.55 (SD 0.12). The HR of spontaneous delivery decreased with increasing placental to fetal ratio (HR 0.013 (95% CI: 0.001–0.121), Wald statistic 14.704 (p < 0.001)), indicating a longer duration of pregnancy with a higher placental to fetal ratio at gestational week 27. The HR of spontaneous delivery also decreased with increasing placental size, but the association was less prominent than the HR associated with placental to fetal ratio (HR 0.997 [95% CI: 0.995–0.999], Wald statistic 7.638 [p = 0.006]). We estimated no association with fetal size (HR 1.001 [95% CI 0.999–1.003], Wald statistic 1.728 [p = 0.189]). Conclusions Our findings suggest that the placental to fetal ratio at gestational week 27 may be an indicator of the remaining duration of pregnancy until the onset of spontaneous labor.

• Langås, Julie Røgler; Hofvind, Solveig Sand-Hanssen; Støer, Nathalie Charlotte; Eskild, Anne & Bjelland, Elisabeth Krefting (2025). Adolescence to Midlife Exercise Trajectories and Age at Natural Menopause: A Population Study of 246 147 Women in Norway. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. doi: 10.1111/1471-0528.18204. Fulltekst i vitenarkiv Vis sammendrag

  Objective - Lifestyle factors influence age at natural menopause, but the role of exercise remains uncertain. We aimed to identify adolescence to midlife exercise trajectories and study the associations of exercise trajectories with age at natural menopause.<p> <p>Design - Retrospective population-based cohort study.<p> <p>Setting - Self-administered questionnaires in the Norwegian breast cancer screening program (BreastScreen Norway) during the years 2005–2016.<p> <p>Population - A total of 246 147 women, aged 50–69 years.<p> <p>Methods - We used latent class mixed model analyses to identify distinct exercise trajectories from adolescence to midlife. The associations were estimated as hazard ratios using Cox proportional hazard models. Adjustments were made for year and country of birth, educational level, number of childbirths, smoking habits and body mass index. We identified four adolescence to midlife exercise trajectories: high (reference), increasing, decreasing and low exercise levels.<p> <p>Main Outcome Measure - Age at natural menopause.<p> <p>Results - The adjusted hazard ratio of reaching menopause was highest for women with constantly low exercise levels as compared to women with constantly high exercise levels (adjusted hazard ratio 1.06, 95% CI: 1.05–1.07). Also, decreasing and increasing exercise levels were associated with higher hazards of reaching menopause (adjusted hazard ratios 1.02; 95% CI: 1.01–1.04 and 1.02; 95% CI: 1.00–1.03, respectively).<p> <p>Conclusions - Women with low exercise levels from adolescence to midlife had the earliest menopause, and women with high exercise levels had the latest. However, the associations were weak, suggesting little influence of exercise on the large variation in age at menopause.

• Flo, Kari; Kulseng, Carl Petter Skaar; Peterson, Helene Fjeldvik; Hillestad, Vigdis; Sommerfelt, Silje & Eskild, Anne (2025). Placental size and umbilical vein volume blood flow. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 104(6), s. 1135–1142. doi: 10.1111/aogs.15110. Fulltekst i vitenarkiv Vis sammendrag

  Introduction The fetus receives oxygen and nutrition from the placenta through the umbilical vein. There is a large variation in placental size and placental size relative to fetal size (placental–fetal ratio). We studied whether placental size or placental–fetal ratio is related to blood flow in the umbilical vein. Material and Methods We performed a prospective study at Akershus University Hospital in Norway and a total of 73 women were examined in gestational weeks 27 and 37. Fifty-six women were examined at both time points. B-mode ultrasound and Doppler ultrasonography were used to measure the umbilical vein volume blood flow per minute. Magnetic resonance imaging was used to measure placental and fetal volume. Pearson's and Spearman's correlation coefficients were applied for estimations of associations. Results In gestational week 27, the umbilical vein volume blood flow was positively correlated with fetal size (Pearson's correlation coefficient r = 0.372, p = 0.003, and Spearman's correlation coefficient r = 0.384, p = 0.002), but not with placental size (Pearson's r = 0.130, p = 0.317, and Spearman's r = − 0.53, p = 0.687) or placental–fetal ratio (Pearson's r = − 0.61, p = 0.641, and Spearman's r = − 0.218, p = 0.092). In gestational week 37, we found positive correlations of the umbilical vein volume blood flow with fetal size (Pearson's r = 0.428, p = <0.001, and Spearman's r = 0.391, p <0.001), placental size (Pearson's r = 0.400, p = 0.001, and Spearman's r = 0.643, p <0.001), and with placental–fetal ratio (Pearson's r = 0.224, p = 0.066, and Spearman's r = 0.266, p = 0.028). Conclusions A large placenta and a high placental–fetal ratio are associated with increased umbilical vein blood flow.

• Langås, Julie Røgler; Eskild, Anne; Hofvind, Solveig Sand-Hanssen & Bjelland, Elisabeth Krefting (2024). The association of adolescent to midlife weight change with age at natural menopause: a population study of 263,586 women in Norway. American Journal of Epidemiology. ISSN 0002-9262. doi: 10.1093/aje/kwae426. Fulltekst i vitenarkiv Vis sammendrag

  Age at menopause varies considerably among women and is linked to health after menopause. Body mass index is associated with age at natural menopause, but the influence of weight change remains unclear. Thus, we studied associations of adolescent to midlife weight change with age at natural menopause. We performed a retrospective population-based cohort study of 263,586 women aged 50-69 years attending BreastScreen Norway (2006-2015). The associations were estimated as hazard ratios (HRs) for having reached menopause using Cox proportional hazard models. We included nine categories of weight change based on recalls of adolescent weight compared to peers and quartiles of midlife weight in kilograms. We adjusted for year and country of birth, education, number of childbirths, height, smoking, and exercise. Women with the largest estimated weight loss had highest hazard of reaching menopause (adjusted HR 1.11, 95% CI: 1.06-1.17) compared to women with estimated stable average weight. Conversely, women with the largest estimated weight gain had lower hazard (adjusted HR 0.96, 95% CI: 0.93-0.99). Women with estimated stable high weight had lowest hazard of reaching menopause (adjusted HR 0.93, 95% CI: 0.90-0.95). Our findings suggest that changes in body weight across the life course may influence the timing of menopause.

• Allotey, John; Archer, Lucinda; Coomar, Dyuti; Snell, Kym Ie; Smuk, Melanie & Oakey, Lucy [Vis alle 49 forfattere av denne artikkelen] (2024). Development and validation of prediction models for fetal growth restriction and birthweight: an individual participant data meta-analysis. Health Technology Assessment. ISSN 1366-5278. 28(47), s. 1–119. doi: 10.3310/DABW4814. Fulltekst i vitenarkiv Vis sammendrag

  Background Fetal growth restriction is associated with perinatal morbidity and mortality. Early identification of women having at-risk fetuses can reduce perinatal adverse outcomes. Objectives To assess the predictive performance of existing models predicting fetal growth restriction and birthweight, and if needed, to develop and validate new multivariable models using individual participant data. Design Individual participant data meta-analyses of cohorts in International Prediction of Pregnancy Complications network, decision curve analysis and health economics analysis. Participants Pregnant women at booking. External validation of existing models (9 cohorts, 441,415 pregnancies); International Prediction of Pregnancy Complications model development and validation (4 cohorts, 237,228 pregnancies). Predictors Maternal clinical characteristics, biochemical and ultrasound markers. Primary outcomes fetal growth restriction defined as birthweight <10th centile adjusted for gestational age and with stillbirth, neonatal death or delivery before 32 weeks’ gestation birthweight. Analysis First, we externally validated existing models using individual participant data meta-analysis. If needed, we developed and validated new International Prediction of Pregnancy Complications models using random-intercept regression models with backward elimination for variable selection and undertook internal-external cross-validation. We estimated the study-specific performance (c-statistic, calibration slope, calibration-in-the-large) for each model and pooled using random-effects meta-analysis. Heterogeneity was quantified using τ2 and 95% prediction intervals. We assessed the clinical utility of the fetal growth restriction model using decision curve analysis, and health economics analysis based on National Institute for Health and Care Excellence 2008 model. Results Of the 119 published models, one birthweight model (Poon) could be validated. None reported fetal growth restriction using our definition. Across all cohorts, the Poon model had good summary calibration slope of 0.93 (95% confidence interval 0.90 to 0.96) with slight overfitting, and underpredicted birthweight by 90.4 g on average (95% confidence interval 37.9 g to 142.9 g). The newly developed International Prediction of Pregnancy Complications-fetal growth restriction model included maternal age, height, parity, smoking status, ethnicity, and any history of hypertension, pre-eclampsia, previous stillbirth or small for gestational age baby and gestational age at delivery. This allowed predictions conditional on a range of assumed gestational ages at delivery. The pooled apparent c-statistic and calibration were 0.96 (95% confidence interval 0.51 to 1.0), and 0.95 (95% confidence interval 0.67 to 1.23), respectively. The model showed positive net benefit for predicted probability thresholds between 1% and 90%. In addition to the predictors in the International Prediction of Pregnancy Complications-fetal growth restriction model, the International Prediction of Pregnancy Complications-birthweight model included maternal weight, history of diabetes and mode of conception. Average calibration slope across cohorts in the internal-external cross-validation was 1.00 (95% confidence interval 0.78 to 1.23) with no evidence of overfitting. Birthweight was underestimated by 9.7 g on average (95% confidence interval −154.3 g to 173.8 g). Limitations We could not externally validate most of the published models due to variations in the definitions of outcomes. Internal-external cross-validation of our International Prediction of Pregnancy Complications-fetal growth restriction model was limited by the paucity of events in the included cohorts. The economic evaluation using the published National Institute for Health and Care Excellence 2008 model may not reflect current practice, and full economic evaluation was not possible due to paucity of data. Future work International Prediction of Pregnancy Complications models’ performance needs to be assessed in routine practice, and their impact on decision-making and clinical outcomes needs evaluation. Conclusion The International Prediction of Pregnancy Complications-fetal growth restriction and International Prediction of Pregnancy Complications-birthweight models accurately predict fetal growth restriction and birthweight for various assumed gestational ages at delivery. These can be used to stratify the risk status at booking, plan monitoring and management.

• Kulseng, Carl Petter Skaar; Sommerfelt, Silje; Flo, Kari; Gjesdal, Kjell Inge; Peterson, Helene Fjeldvik & Hillestad, Vigdis [Vis alle 7 forfattere av denne artikkelen] (2024). Placental size at gestational week 27 and 37: The associations with pulsatility index in the uterine and the fetal-placental arteries. Placenta. ISSN 0143-4004. 145, s. 45–50. doi: 10.1016/j.placenta.2023.11.014. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Fetal growth restriction is known to be related to decreased fetal and placental blood flow. It is not known, however, whether placental size is related to fetal and placental blood flow. We studied the correlations of intrauterine placental volume and placental-fetal-ratio with pulsatility index (PI) in the uterine arteries, fetal middle cerebral artery, and umbilical artery. Methods We followed a convenience sample of 104 singleton pregnancies, and we measured placental and fetal volumes using magnetic resonance imaging (MRI) at gestational week 27 and 37 (n = 89). Pulsatility index (PI) was measured using Doppler ultrasound. We calculated cerebroplacental ratio as fetal middle cerebral artery PI/umbilical artery PI and placental-fetal-ratio as placental volume (cm3)/fetal volume (cm3). Results At gestational week 27, placental volume was negatively correlated with uterine artery PI (r = −0.237, p = 0.015, Pearson's correlation coefficient), and positively correlated with fetal middle cerebral artery PI (r = 0.247, p = 0.012) and cerebroplacental ratio (r = 0.208, p = 0.035). Corresponding correlations for placental-fetal-ratio were −0.273 (p = 0.005), 0.233 (p = 0.018) and 0.183 (p = 0.064). Umbilical artery PI was not correlated with placental volume. At gestational week 37, we found weaker and no significant correlations between placental volume and the pulsatility indices. Conclusions Our results suggest that placental size is correlated with placental and fetal blood flow at gestational week 27.

• Eskild, Anne; Skau, Irene; Haavaldsen, Camilla; Saugstad, Ola Didrik & Grytten, Jostein Ivar (2024). Short inter-pregnancy interval and birthweight: a reappraisal based on a follow-up study of all women in Norway with two singleton deliveries during 1970–2019. European Journal of Epidemiology (EJE). ISSN 0393-2990. 39(8), s. 905–914. doi: 10.1007/s10654-024-01148-y. Fulltekst i vitenarkiv Vis sammendrag

  We studied mean changes in birthweight from the first to the second delivery according to length of the inter-pregnancy interval. We also studied recurrence risk of low birthweight, preterm birth and perinatal death. We followed all women in Norway from their first to their second singleton delivery at gestational week 22 or beyond during the years 1970–2019, a total of 654 100 women. Data were obtained from the Medical Birth Registry of Norway. Mean birthweight increased from the first to the second delivery, and the increase was highest in pregnancies conceived < 6 months after the first delivery; adjusted mean birthweight increase 227 g (g) (95% CI; 219–236 g), 90 g higher than in pregnancies conceived 6–11 months after the first delivery (137 g (95% CI; 130–144 g)). After exclusion of women with a first stillbirth, the mean increase in birthweight at inter-pregnancy interval < 6 months was attenuated (152 g, 95% CI; 143–160 g), but remained higher than at longer inter-pregnancy intervals. This finding was particularly prominent in women > 35 years (218 g, 95% CI; 139 –298 g). In women with a first live born infant weighing < 2500 g, mean birthweight increased by around 1000 g to the second delivery, and the increase was most prominent at < 6 months inter-pregnancy interval. We found increased recurrence risk of preterm birth at inter-pregnancy interval < 6 months, but no increased recurrence risk of low birthweight, small for gestational age infant or perinatal death. In conclusion, we found the highest mean increase in birthweight when the inter-pregnancy interval was short. Our results do not generally discourage short pregnancy intervals.

• Sagberg, Karianne; Eskild, Anne; Sommerfelt, Silje; Halle, Tuva Kristine Toresdatter; Hillestad, Vigdis & Haavaldsen, Camilla (2024). Two-dimensional (2D) placental ultrasound measurements – The correlation with placental volume measured by magnetic resonance imaging (MRI). Placenta. ISSN 0143-4004. 149, s. 7–12. doi: 10.1016/j.placenta.2024.02.010. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Information about placental size in ongoing pregnancies may aid the identification of pregnancies with increased risk of adverse outcome. Placental volume can be measured using magnetic resonance imaging (MRI). However, this method is not universally available in antenatal care. Ultrasound is the diagnostic tool of choice in pregnancy. Therefore, we studied whether simple two-dimensional (2D) ultrasound placental measurements were correlated with placental volume measured by MRI. Methods We examined a convenience sample of 104 ongoing pregnancies at gestational week 27, using both ultrasound and MRI. The ultrasound measurements included placental length, width and thickness. Placental volume was measured using MRI. The correlation between each 2D placental ultrasound measurement and placental volume was estimated by applying Pearson's correlation coefficient (r). Results Mean placental length was 17.2 cm (SD 2.1 cm), mean width was 14.7 cm (SD 2.1 cm), and mean thickness was 3.2 cm (SD 0.6 cm). Mean placental volume was 536 cm3 (SD 137 cm3). The 2D ultrasound measurements showed poor correlation with placental volume (placental length; r = 0.27, width; r = 0.37, and thickness r = 0.13). Discussion Simple 2D ultrasound measurements of the placenta were poorly correlated with placental volume and cannot be used as proximate measures of placental volume. Our finding may be explained by the large variation between pregnancies in intrauterine placental shape.

• Peterson, Helene Fjeldvik; Eskild, Anne; Sommerfelt, Silje & Hillestad, Vigdis (2023). Placental size at gestational week 36: Comparisons between ongoing pregnancies and deliveries. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 103, s. 85–92. doi: 10.1111/aogs.14700. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Introduction We aimed to compare placental size and placental size relative to fetal size (ratio) in ongoing pregnancies examined by magnetic resonance imaging (MRI) at gestational week 36 with placental size among all deliveries at gestational week 36 during the same time period. Material and methods Ongoing unselected singleton pregnancies ( n  = 89) were examined by MRI at median gestational week 36+5 days during 2017–2018, and placental and fetal volumes (cm 3 ) were calculated. The placental size and ratio in ongoing pregnancies were compared with placental size and ratio among all deliveries in Norway at gestational week 36 (median gestational week 36+4 days) during 2016–2019 ( n  = 5582). For comparison of size, we converted volume (cm 3 ) in ongoing pregnancies into grams as: cm 3  × 1.05 (density of placental and fetal tissue). Results In ongoing pregnancies, median placental size was 873  (interquartile range [IQR] 265) grams and median size of all delivered placentas was 613 (IQR 290) grams. Placental size was smaller among the delivered placentas independent of delivery mode: 760 (IQR 387) grams among elective cesarean deliveries ( n  = 465) and 590 (IQR 189) grams among vaginal deliveries after spontaneous onset of labor ( n  = 2478). Median ratio in ongoing pregnancies was higher than among deliveries: 0.31 (IQR 0.08) vs 0.21 (IQR 0.08). The ratio was higher in ongoing pregnancies independent of delivery mode: 0.24 (IQR 0.17) among elective cesarean deliveries vs 0.21 (IQR 0.05) among vaginal deliveries after spontaneous onset of labor. Conclusions The placenta is larger in ongoing pregnancies than among deliveries. This finding suggests that placental size decreases during labor and delivery, possibly by transfer of blood to the fetus. Our finding also suggests that reference values of placental size based on delivered placentas are not valid for ongoing pregnancies.

• Langås, Julie Røgler; Eskild, Anne; Hofvind, Solveig Sand-Hanssen & Bjelland, Elisabeth Krefting (2023). The dose-response relationship of pre-menopausal alcohol consumption with age at menopause: a population study of 280 497 women in Norway. International Journal of Epidemiology. ISSN 0300-5771. 52(6), s. 1951–1958. doi: 10.1093/ije/dyad129. Fulltekst i vitenarkiv Vis sammendrag

  Background: Previous research suggests that alcohol consumption is associated with high age at menopause. Yet, knowledge about the dose– response relationship is inconsistent. Thus, we studied the pattern of the association of pre-menopausal alcohol consumption with age at natural menopause.<p> <p>Methods: We performed a retrospective population-based study using self-reported data from 280 497 women aged 50–69 years attending the Norwegian breast cancer screening programme (BreastScreen Norway) during 2006–15. Associations of weekly alcohol consumption between the age of 20 and 49 years with age at menopause were estimated as hazard ratios (HRs) using Cox proportional hazard models with restricted cubic splines to allow for non-linear associations. We adjusted for year and place of birth, number of childbirths, educational level, body mass index and smoking habits. <p>Results: Mean age at natural menopause was 51.20 years (interquartile range: 49–54 years). The adjusted HR of reaching menopause was highest for women with no alcohol consumption (reference) and the HR decreased by alcohol consumption up to 50 grams per week (adjusted HR 0.87; 95% CI: 0.86–0.88). Above 50 grams, there was no further decrease in the HR of reaching menopause (P for non-linearity of <0.001). <p>Conclusions: Women who did not consume alcohol were youngest at menopause. The lack of a dose–response association among alcohol consumers implies virtually no relation of alcohol consumption with age at menopause. Our findings may suggest that characteristics of the women who did not consume alcohol, not accounted for in the data analyses, explain their younger age at menopause.

• Eskild, Anne; Skau, Irene; Grytten, Jostein Ivar & Haavaldsen, Camilla (2023). Inter-pregnancy interval and placental weight. A population based follow-up study in Norway. Placenta. ISSN 0143-4004. 144, s. 38–44. doi: 10.1016/j.placenta.2023.11.003. Fulltekst i vitenarkiv Vis sammendrag

  Introduction We studied changes in placental weight from the first to the second delivery according to length of the inter-pregnancy interval. Methods We followed all women in Norway from their first to their second successive singleton pregnancy during the years 1999–2019, a total of 271 184 women. We used data from the Medical Birth Registry of Norway and studied changes in placental weight (in grams (g)) according to the length of the inter-pregnancy. Adjustments were made for year and maternal age at first delivery, changes in the prevalence of maternal diseases (hypertension and diabetes), and a new father to the second pregnancy. Results Mean placental weight increased from 655 g at the first delivery to 680 g at the second. The adjusted increase in placental weight was highest at inter-pregnancy intervals <6 months; 38.2 g (95 % CI 33.0g–43.4 g) versus 23.2 g (95 % CI 18.8g–27.7 g) at inter-pregnancy interval 6–17 months. At inter-pregnancy intervals ≥18 months, placental weight remained higher than at the first delivery, but was non-different from inter-pregnancy intervals 6–17 months. Also, after additional adjustment for daily smoking and body mass index in sub-samples, we found the highest increase in placental weight at the shortest inter-pregnancy interval. We estimated no difference in gestational age at delivery or placental to birthweight ratio according to inter-pregnancy interval. Discussion Placental weight increased from the first to the second pregnancy, and the increase was most pronounced at short inter-pregnancy intervals. The biological causes and implications of such findings remain to be studied.

• Meinich, Tale Jeanette & Eskild, Anne (2023). Har svangerskapsavbrudd betydning for nedgangen i antall fødsler? Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 143(17), s. 1500–1502. doi: 10.4045/tidsskr.23.0337. Fulltekst i vitenarkiv Vis sammendrag

  BAKGRUNN Fødselsratene i Norge er fallende, og stadig færre får flere enn to barn. Svangerskapsavbrudd kan påvirke fødselstallene. Vi ønsket å studere fordelingen av graviditeter i Norge etter paritet, og om andelen av graviditetene som endte i svangerskapsavbrudd har endret seg. MATERIALE OG METODE For perioden 2008–20 innhentet vi tall på graviditeter i Norge basert på antall fødsler i Medisinsk fødselsregister og antall svangerskapsavbrudd i Abortregisteret. Vi regnet ut andelen svangerskapsavbrudd fordelt etter paritet og år. RESULTATER Summen av fødsler og aborter per år falt med 16,4 % i studieperioden. Den absolutte nedgangen var mest uttalt blant kvinner uten tidligere fødsler, fra 34 647 i 2008 til 28 606 i 2020 (17,4 % nedgang). Blant disse falt andelen graviditeter som endte med svangerskapsavbrudd, fra 25,2 % til 20,5 %. Andelen med svangerskapsavbrudd blant kvinner med to, tre, fire eller flere tidligere fødsler var henholdsvis 26,1 %, 34,6 % og 28,2 % i 2008, og 26,1 %, 34,0 % og 29,1 % i 2020. FORTOLKNING Både antall fødsler og antall svangerskapsavbrudd i Norge falt i perioden 2008–20, i alle paritetsgrupper. Reduksjonen var mest uttalt hos kvinner uten tidligere fødsler. Antall svangerskapsavbrudd falt mer enn antall fødsler. Svangerskapsavbrudd kan derfor ikke forklare at fødselsratene i Norge faller.

• Kulseng, Carl Petter Skaar; Hillestad, Vigdis; Eskild, Anne & Gjesdal, Kjell Inge (2023). Automatic placental and fetal volume estimation by a convolutional neural network. Placenta. ISSN 0143-4004. 134, s. 23–29. doi: 10.1016/j.placenta.2023.02.009. Fulltekst i vitenarkiv
• Peterson, Helene Fjeldvik; Eskild, Anne; Sommerfelt, Silje; Gjesdal, Kjell Inge; Borthne, Arne Sigmund & Mørkrid, Lars [Vis alle 7 forfattere av denne artikkelen] (2022). Percentiles of intrauterine placental volume and placental volume relative to fetal volume: A prospective magnetic resonance imaging study. Placenta. ISSN 0143-4004. 121, s. 40–45. doi: 10.1016/j.placenta.2022.02.023. Fulltekst i vitenarkiv Vis sammendrag

  Introduction We aimed to provide percentiles of intrauterine placental growth and placental growth relative to fetal growth (placental to fetal ratio) by measuring placental and fetal volumes by magnetic resonance imaging (MRI). Methods In this prospective study, 107 unselected singleton pregnancies were examined by MRI at gestational week 27 and 37. Based on the estimated volumes of the placenta and the fetus, we calculated median and percentiles at gestational weeks 27 and 37. Results Median placental volume at gestational week 27 was 513 cm3 (Inter Quartile Range (IQR) 182 cm3), and 831 cm3 (IQR 252 cm3) at week 37. The 10th – 90th percentiles included placental volumes between 392 and 717 cm3 at gestational week 27, and 631–1087 cm3 at week 37. The placental to fetal ratio was significantly higher at gestational week 27 than at week 37, with a median ratio of 0.54 (IQR 0.18) and 0.31 (IQR 0.08), respectively (p < 0.001). The 10th-90th percentiles included placental to fetal ratios between 0.43 and 0.73 at gestational week 27 and 0.25–0.39 at week 37. Discussion At gestational week 27, the placental volume was about half the size of the fetal volume, whereas at week 37, the placental volume was about one third of the fetal volume. This finding suggests that placental growth was less prominent than fetal growth after gestational week 27. Knowledge about the distribution of intrauterine placental size in the general population of pregnancies are prerequisites for diagnosing abnormal placental size.

• Sheikh, Jameela; Allotey, John; Kew, Tania; Fernández-Félix, Borja M.; Zamora, Javier & Khalil, Asma [Vis alle 50 forfattere av denne artikkelen] (2022). Effects of race and ethnicity on perinatal outcomes in high-income and upper-middle-income countries: an individual participant data meta-analysis of 2 198 655 pregnancies. The Lancet. ISSN 0140-6736. 10(400), s. 2049–2062. doi: 10.1016/S0140-6736(22)01191-6. Fulltekst i vitenarkiv Vis sammendrag

  Background Existing evidence on the effects of race and ethnicity on pregnancy outcomes is restricted to individual studies done within specific countries and health systems. We aimed to assess the impact of race and ethnicity on perinatal outcomes in high-income and upper-middle-income countries, and to ascertain whether the magnitude of disparities, if any, varied across geographical regions. Methods For this individual participant data (IPD) meta-analysis we used data from the International Prediction of Pregnancy Complications (IPPIC) Network of studies on pregnancy complications; the full dataset comprised 94 studies, 53 countries, and 4 539 640 pregnancies. We included studies that reported perinatal outcomes (neonatal death, stillbirth, preterm birth, and small-for-gestational-age babies) in at least two racial or ethnic groups (White, Black, south Asian, Hispanic, or other). For our two-step random-effects IPD meta-analysis, we did multiple imputations for confounder variables (maternal age, BMI, parity, and level of maternal education) selected with a directed acyclic graph. The primary outcomes were neonatal mortality and stillbirth. Secondary outcomes were preterm birth and a small-for-gestational-age baby. We estimated the association of race and ethnicity with perinatal outcomes using a multivariate logistic regression model and reported this association with odds ratios (ORs) and 95% CIs. We also did a subgroup analysis of studies by geographical region. Findings 51 studies from 20 high-income and upper-middle-income countries, comprising 2 198 655 pregnancies, were eligible for inclusion in this IPD meta-analysis. Neonatal death was twice as likely in babies born to Black women than in babies born to White women (OR 2·00, 95% CI 1·44–2·78), as was stillbirth (2·16, 1·46–3·19), and babies born to Black women were at increased risk of preterm birth (1·65, 1·46–1·88) and being small for gestational age (1·39, 1·13–1·72). Babies of women categorised as Hispanic had a three-times increased risk of neonatal death (OR 3·34, 95% CI 2·77–4·02) than did those born to White women, and those born to south Asian women were at increased risk of preterm birth (OR 1·26, 95% CI 1·07–1·48) and being small for gestational age (1·61, 1·32–1·95). The effects of race and ethnicity on preterm birth and small-for-gestational-age babies did not vary across regions. Interpretation Globally, among underserved groups, babies born to Black women had consistently poorer perinatal outcomes than White women after adjusting for maternal characteristics, although the risks varied for other groups. The effects of race and ethnicity on adverse perinatal outcomes did not vary by region.

• Blix, Ellen; Eskild, Anne; Skau, Irene & Grytten, Jostein Ivar (2022). The impact of the introduction of intrapartum fetal ECG ST segment analysis. A population study. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 101(7), s. 809–818. doi: 10.1111/aogs.14347. Fulltekst i vitenarkiv Vis sammendrag

  Introduction ST segment analysis (STAN) of the fetal electrocardiogram was introduced as an adjunct to cardiotocography for intrapartum fetal monitoring 30 years ago. We examined the impact of the introduction of STAN on changes in the occurrence of fetal and neonatal deaths, Apgar scores of <7 at 5 min, intrapartum cesarean sections, and instrumental vaginal deliveries while controlling for time- and hospital-specific trends and maternal risk factors. Material and Methods Data were retrieved from the Medical Birth Registry of Norway from 1985 to 2014. Individual data were linked to the Education Registry and the Central Person Registry. The study sample included 1 132 022 singleton births with a gestational age of 36 weeks or beyond. Information about the year of STAN introduction was collected from every birth unit in Norway using a questionnaire. Our data structure consisted of a hospital-year panel. We applied a linear probability model with hospital-fixed effects and with adjustment for potentially confounding factors. The prevalence of the outcomes before and after the introduction of STAN were compared within each birth unit. Results In total, 23 birth units, representing 76% of all births in Norway, had introduced the STAN technology. During the study period, stillbirths declined from 2.6 to 1.9 per 1000 births, neonatal deaths declined from 1.7 to 0.7 per 1000 live births, babies with Apgar score <7 at 5 min after birth increased from 7.4 to 9.5 per 1000 births, intrapartum cesarean sections increased from 6.4% to 9.5%, and instrumental vaginal deliveries increased from 7.8% to 10.9%. Our analyses found that the introduction of STAN was not associated with the decline in proportion of stillbirths (p =0.76) and neonatal deaths (p =0.76) or with the increase in intrapartum cesarean sections (p =0.92) and instrumental vaginal deliveries (p =0.78). However, it was associated with the increased occurrence of Apgar score <7 at 5 min (p =0.01). Conclusions There is no evidence that the introduction of STAN contributed to changes in the rates of stillbirths, neonatal deaths, intrapartum cesarean sections, or instrumental vaginal deliveries. There was an association between the introduction of STAN and a small increase in neonates with low Apgar scores.

• Eskild, Anne; Mørkrid, Lars; Mortensen, Siri Beisland & Leegaard, Truls Michael (2022). Prevalence of antibodies against SARS-CoV-2 among pregnant women in Norway during the period December 2019 through December 2020. Epidemiology and Infection. ISSN 0950-2688. 150, s. 1–3. doi: 10.1017/S0950268822000073. Fulltekst i vitenarkiv Vis sammendrag

  We studied severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence among pregnant women in Norway by including all women who were first trimester pregnant (n = 6520), each month from December 2019 through December 2020, in the catchment region of Norway's second-largest hospital. We used sera that had been frozen stored after compulsory testing for syphilis antibodies in antenatal care. The sera were analysed with the Elecsys® Anti-SARS-CoV-2 immunoassay (Roche Diagnostics, Cobas e801). This immunoassay detects IgG/IgM against SARS-CoV-2 nucleocapsid antigen. Sera with equivocal or positive test results were retested with the Liaison® SARS-CoV-2 S1/S2 IgG (DiaSorin), which detects IgG against the spike (S)1 and S2 protein on the SARS-CoV-2 virus. In total, 98 women (adjusted prevalence 1.7%) had SARS CoV-2 antibodies. The adjusted seroprevalence increased from 0.3% (1/445) in December 2019 to 5.7% (21/418) in December 2020. Out of the 98 seropositive women, 36 (36.7%) had serological signs of current SARS-CoV-2 infection at the time of serum sampling, and the incidence remained low during the study period. This study suggests that SARS CoV-2 was present in the first half of December 2019, 6 weeks before the first case was recognised in Norway. The low occurrence of SARS-CoV-2 infection during 2020, may be explained by high compliance to extensive preventive measures implemented early in the epidemic.

• Haavaldsen, Camilla; Morken, Nils-Halvdan; Saugstad, Ola Didrik & Eskild, Anne (2022). Is the increasing prevalence of labor induction accompanied by changes in pregnancy outcomes? An observational study of all singleton births at gestational weeks 37–42 in Norway during 1999–2019. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. s. 1–16. doi: 10.1111/aogs.14489. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Induction of labor is often performed to prevent adverse perinatal and maternal outcomes, and has become increasingly common. We studied whether changes in prevalence of labor induction in gestational weeks 37–42 weeks were accompanied by changes in adverse pregnancy outcomes or mode of delivery. Material and methods We used data from the Medical Birth Registry of Norway, and included all singleton births in gestational weeks 37–42 in Norway, 1999–2019 (n = 1 127 945). We calculated the prevalence of labor induction and outcome measures according to year of birth. We repeated these calculations for each gestational week at birth. Results The prevalence of labor induction increased from 9.7% to 25.9%, and the increase was particularly high in gestational week 41. A modest decline in fetal deaths was observed in all gestational weeks, except gestational week 41. The overall decline was from 0.18% in 1999–2004 to 0.13% during 2015–2019. There were no overall changes in other perinatal outcomes. The prevalence of postpartum hemorrhage ≥500 ml increased from 11.4% in 1999 to 30.1% in 2019, and operative deliveries increased slightly. The prevalence of acute cesarean section increased from 6.5% to 9.3%, whereas vacuum and/or forceps assisted deliveries increased from 7.8% to 10.4%. Conclusions A high increase in labor inductions was accompanied by a modest decline in fetal deaths, but no decline in other adverse perinatal outcomes. In settings where the prevalence of adverse perinatal outcomes is low, the beneficial effect of increased use of labor induction may not outweigh the side effects or the costs.

• Riise, Hilde Kristin Refvik; Igland, Jannicke; Sulo, Gerhard; Iversen, Marjolein M.; Graue, Marit & Eskild, Anne [Vis alle 8 forfattere av denne artikkelen] (2022). Is the risk of cardiovascular disease in women with pre-eclampsia modified by very low or very high offspring birth weight? A nationwide cohort study in Norway. BMJ Open. 12(4), s. 1–8. doi: 10.1136/bmjopen-2021-055467. Fulltekst i vitenarkiv Vis sammendrag

  Objectives To examine whether the risk of cardiovascular disease (CVD) in women with pre-eclampsia is modified by very low or very high offspring birth weight. Further, we studied whether diabetes in pregnancy modified this risk. Design Nationwide cohort study. Setting Norwegian population registries. Participants 618 644 women who gave birth to their first child during 1980–2009. Methods The women were followed from delivery until the development of CVD or censoring, by linkage of the Medical Birth Registry of Norway to the Cardiovascular Disease in Norway project, and the Norwegian Cause of Death Registry. Primary outcome measure: CVD. Results Compared with normotensive women with normal offspring birth weight, women with pre-eclampsia had increased risk of CVD (HR 2.16; 95% CI 2.05 to 2.26). The CVD risk was even higher when pre-eclampsia was accompanied with a large for gestational age offspring (LGA, z-score >2.0) (HR 2.57; 95% CI 2.08 to 3.18). Women with pre-eclampsia and a small for gestational age offspring (SGA, z-score <−2.0) had an HR of 1.54 (95% CI 1.23 to 1.93) compared with normotensive women with normal offspring birth weight. Also, women with diabetes had increased CVD risk, but no additional risk associated with an LGA or SGA offspring. Conclusions Women with pre-eclampsia and an LGA offspring had higher risk of CVD than pre-eclamptic women with a normal weight (z-score −2.0 to 2.0) or SGA offspring. These findings suggest that factors causing pre-eclampsia and an LGA offspring are also linked to development of CVD.

• Gottschalk, Marthe Sørli; Eskild, Anne; Hofvind, Solveig & Bjelland, Elisabeth Krefting (2021). The relation of number of childbirths with age at natural menopause: a population study of 310 147 women in Norway. Human Reproduction. ISSN 0268-1161. 37(2), s. 333–340. doi: 10.1093/humrep/deab246. Fulltekst i vitenarkiv Vis sammendrag

  Study question: Does age at natural menopause increase with increasing of number of childbirths? Summary answer: Age at menopause increased with increasing number of childbirths up to three childbirths; however, we found no further increase in age at menopause beyond three childbirths. What is known already: Pregnancies interrupt ovulation, and a high number of pregnancies have therefore been assumed to delay menopause. Previous studies have had insufficient statistical power to study women with a high number of childbirths. Thus, the shape of the association of number of childbirths with age at menopause remains unknown. Study design, size, duration: A retrospective population study of 310 147 women in Norway who were 50–69 years old at data collection. Participants/materials, setting, methods: The data were obtained by two self-administered questionnaires completed by women attending BreastScreen Norway, a population-based screening program for breast cancer. The associations of number of childbirths with age at menopause were estimated as hazard ratios by applying Cox proportional hazard models, adjusting for the woman’s year of birth, cigarette smoking, educational level, country of birth, oral contraceptive use and body mass index. Main results and the role of chance: Women with three childbirths had the highest mean age at menopause (51.36 years; 95% CI: 51.33–51.40 years), and women with no childbirths had the lowest (50.55 years; 95% CI: 50.48–50.62 years). Thus, women with no childbirths had higher hazard ratio of reaching menopause compared to women with three childbirths (reference group) (adjusted hazard ratio, 1.24; 95% CI: 1.22–1.27). Beyond three childbirths, we estimated no further increase in age at menopause. These findings were confirmed in sub-analyses among (i) women who had never used hormonal intrauterine device and/or systemic menopausal hormonal therapy; (ii) women who were born before 1950 and (iii) women who were born in 1950 or after. Limitations, reasons for caution: Information about age at menopause was based on self-reports. Wider implications of the findings: If pregnancies truly delay menopause, one would expect that women with the highest number of childbirths had the highest age at menopause. Our results question the assumption that interrupted ovulation during pregnancy delays menopause.

• Grytten, Jostein Ivar; Skau, Irene & Eskild, Anne (2021). Does the use of Doppler ultrasound reduce fetal mortality? A population study of all deliveries in Norway 1990-2014. International Journal of Epidemiology. ISSN 0300-5771. 50(6), s. 2038–2047. doi: 10.1093/ije/dyab098. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Background The aim of the present study was to examine the effect that the introduction of Doppler ultrasound in obstetric care has had on fetal death in Norway. One mechanism by which Doppler ultrasound may reduce fetal death may be through the increased use of Caesarean delivery. Therefore, we also examined the effect that the use of Doppler ultrasound has had on the use of Caesarean delivery. Methods The Medical Birth Registry of Norway provided detailed medical information for ∼1.2 million deliveries from 1990 to 2014. Information about the year of introduction of Doppler ultrasound was collected directly from the maternity units, using a questionnaire. The data were analysed using a hospital fixed-effects regression model with fetal death as the outcome measure. The key independent variable was the introduction of Doppler ultrasound at each maternity ward. Hospital-specific trends and risk factors of the mother for fetal death were included as covariates. Results For pre-term deliveries, the introduction of Doppler ultrasound contributed to a reduction in fetal death of ∼30% and to an increase in planned Caesarean section of ∼15%. There were no effects for emergency Caesarean sections or inductions pre-term. The introduction of Doppler ultrasound had no effect on fetal death or Caesarean section for term deliveries. Conclusions The introduction of Doppler ultrasound during the 1990s and 2000s made a significant contribution to the decline in the number of pre-term fetal deaths in Norway. Increased use of Caesarean section may have contributed to this reduction.

• Sagberg, Karianne; Eskild, Anne; Sommerfelt, Silje; Gjesdal, Kjell-Inge; Higgins, Lucy E. & Borthne, Arne Sigmund [Vis alle 7 forfattere av denne artikkelen] (2021). Placental volume in gestational week 27 measured by three-dimensional ultrasound and magnetic resonance imaging. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 100(8), s. 1412–1418. doi: 10.1111/aogs.14115. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Ultrasound is the diagnostic tool of choice in pregnancy. We lack valid ultrasound methods for placental size measurements. Our aim was therefore to compare three-dimensional (3D) ultrasound with magnetic resonance imaging (MRI) for measurements of placental volume. Material and methods We measured placental volume by 3D ultrasound and MRI in 100 unselected pregnancies at 27 weeks of gestation (25+4–28+4 weeks). The 3D ultrasound acquisitions were analyzed offline, and the placental outline was manually traced using the virtual organ computer-aided analysis (VOCAL) 30° rotational technique. The MRI examinations included a T2-weighted gradient echo sequence in the sagittal plane, with 5-mm slices through the entire uterus. The placental outline was manually traced in each slice. The correlation between 3D ultrasound and MRI placental volumes was estimated by intraclass correlation coefficients. Bland-Altman analysis was applied to visualize systematic bias and limits of agreement, in which the ratio MRI placental volume/3D ultrasound placental volume was plotted against the average of the two methods. Results The intraclass correlation coefficient between 3D ultrasound and MRI measurements was 0.49 (95% confidence interval 0.33-0.63). In general, 3D ultrasound measured smaller placental volumes (median 373 cm3, interquartile range 309-434 cm3) than MRI (median 507 cm3, interquartile range 429-595 cm3) and the systematic bias was 1.44. The 95% limits of agreement between the two methods were wide (0.68-2.21). Conclusions We found poor to moderate correlation between 3D ultrasound and MRI placental volume measurements. Generally, 3D ultrasound measured smaller placental volumes than MRI, suggesting that 3D ultrasound failed to visualize the entire placenta. Our findings may hopefully contribute to the improvement of ultrasound methods for placental measurements.

• Strøm-Roum, Ellen Marie; Jukic, Anne M. & Eskild, Anne (2021). Offspring birthweight and placental weight—does the type of maternal diabetes matter? A population-based study of 319 076 pregnancies. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. s. 1–8. doi: 10.1111/aogs.14217. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Our aim was to estimate the difference in birthweight and in placental weight in pregnancies with type 1 diabetes, type 2 diabetes, and gestational diabetes compared with pregnancies without diabetes. Material and methods By using data from the Medical Birth Registry of Norway during the years 2009–2017, we included 319 076 singleton pregnancies with delivery after the 21st week of pregnancy. We used linear regression analyses to estimate the difference in birthweight and in placental weight in grams (g) in pregnancies with type 1 diabetes, type 2 diabetes, and gestational diabetes, using pregnancies without diabetes as the reference. Adjustments were made for pregnancy duration and pre-pregnancy body mass index. Results In pregnancies without diabetes, mean crude birthweight was 3527 g (SD 552 g). The adjusted mean birthweight was 525 g (95% CI 502–548 g) higher in pregnancies with type 1 diabetes compared with pregnancies without diabetes. In pregnancies with type 2 diabetes, and pregnancies with gestational diabetes, birthweights were 192 g (95% CI 160–223 g) and 102 g (95% CI 93–110 g) higher, respectively. Mean crude placental weight was 664 g (SD 147 g) in pregnancies without diabetes. Compared with pregnancies without diabetes, the adjusted mean placental weight was 109 g (95% CI 101–116 g) higher in pregnancies with type 1 diabetes, 50 g (95% CI 39–60 g) higher in pregnancies with type 2 diabetes, and 31 g (95% CI 28–34 g) higher in pregnancies with gestational diabetes. Conclusions The increase in birthweight and in placental weight associated with maternal diabetes was most pronounced for type 1 diabetes, followed by type 2 diabetes, and gestational diabetes.

• Eskild, Anne; Skau, Irene; Haavaldsen, Camilla & Grytten, Jostein Ivar (2021). A.Eskild og medarbeiderne svarer. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 141(12). doi: 10.4045/tidsskr.21.0584. Fulltekst i vitenarkiv
• Gottschalk, Marthe Sørli; Eskild, Anne; Hofvind, Solveig; Gran, Jon Michael & Bjelland, Elisabeth Krefting (2020). Temporal trends in age at menarche and age at menopause: a population study of 312 656 women in Norway. Human Reproduction. ISSN 0268-1161. 35(2), s. 464–471. doi: 10.1093/humrep/dez288. Fulltekst i vitenarkiv Vis sammendrag

  Abstract STUDY QUESTION Have mean age at menarche or mean age at natural menopause changed from the 1939 birth cohort to the 1964 birth cohort? SUMMARY ANSWER We estimated a minor decrease in mean age at menarche and an increase by nearly 3 years in mean age at natural menopause. WHAT IS KNOWN ALREADY In the Western world, age at menarche decreased across birth cohorts from the early 1800s until the 1950s. Whether mean age at menarche has continued to decrease in birth cohorts after the 1950s remains uncertain. It is also uncertain whether mean age at natural menopause has changed across birth cohorts. STUDY DESIGN, SIZE, DURATION We performed a retrospective population study of 312 656 women who were born in Norway during the years 1936–1964. PARTICIPANTS/MATERIALS, SETTING, METHODS The data were obtained by two self-administered questionnaires from women who participated in the Norwegian breast cancer screening program (BreastScreen Norway) during the years 2006–2014. We used flexible parametric survival models with restricted cubic splines to estimate mean age at menarche, mean age at menopause and mean number of years between menarche and menopause according to the women’s year of birth. The women who were still having menstrual periods contributed with follow-up time until the time of data collection, and the women who had reported surgical removal of the uterus and/or both ovaries prior to natural menopause contributed with follow-up time until the time of surgery. MAIN RESULTS AND THE ROLE OF CHANCE The mean age at menarche was 13.42 years (95% CI: 13.40–13.44 years) among women born during 1936–1939, and it was 13.24 years (95% CI: 13.22–13.25 years) among women born during 1960–1964. The mean age at natural menopause increased from 50.31 years (95% CI: 50.25–50.37 years) among women born during 1936–1939 to 52.73 years (95% CI: 52.64–52.82 years) among women born during 1960–1964. The mean number of years between menarche and menopause increased from 36.83 years (95% CI: 36.77–36.89 years) to 40.22 years (95% CI: 40.11–40.34 years). LIMITATIONS, REASONS FOR CAUTION Information about age at menarche and age at menopause was based on self-reports. WIDER IMPLICATIONS OF THE FINDINGS Late menopause is associated with increased risk of breast cancer but also with increased life expectancy. Thus, higher mean age at menopause may partly explain the increase in breast cancer incidence after menopause and the increase in life expectancy in recent time. Also, a longer interval between menarche and menopause could suggest that the number of years of female fecundity has increased. STUDY FUNDING/COMPETING INTEREST(S) This work was funded by the South-Eastern Norway Regional Health Authority [grant number 2016112 to M.S.G.] and by the Norwegian Cancer Society [grant number 6863294-2015 to E.K.B.]. The authors declare no conflicts of interest.

• Snell, Kym I.E.; Allotey, John; Smuk, Melanie; Hooper, Richard; Chan, Claire & Ahmed, Asif [Vis alle 60 forfattere av denne artikkelen] (2020). External validation of prognostic models predicting pre-eclampsia: individual participant data meta-analysis. BMC Medicine. 18, s. 1–18. doi: 10.1186/s12916-020-01766-9. Fulltekst i vitenarkiv Vis sammendrag

  Background Pre-eclampsia is a leading cause of maternal and perinatal mortality and morbidity. Early identification of women at risk during pregnancy is required to plan management. Although there are many published prediction models for pre-eclampsia, few have been validated in external data. Our objective was to externally validate published prediction models for pre-eclampsia using individual participant data (IPD) from UK studies, to evaluate whether any of the models can accurately predict the condition when used within the UK healthcare setting. Methods IPD from 11 UK cohort studies (217,415 pregnant women) within the International Prediction of Pregnancy Complications (IPPIC) pre-eclampsia network contributed to external validation of published prediction models, identified by systematic review. Cohorts that measured all predictor variables in at least one of the identified models and reported pre-eclampsia as an outcome were included for validation. We reported the model predictive performance as discrimination (C-statistic), calibration (calibration plots, calibration slope, calibration-in-the-large), and net benefit. Performance measures were estimated separately in each available study and then, where possible, combined across studies in a random-effects meta-analysis. Results Of 131 published models, 67 provided the full model equation and 24 could be validated in 11 UK cohorts. Most of the models showed modest discrimination with summary C-statistics between 0.6 and 0.7. The calibration of the predicted compared to observed risk was generally poor for most models with observed calibration slopes less than 1, indicating that predictions were generally too extreme, although confidence intervals were wide. There was large between-study heterogeneity in each model’s calibration-in-the-large, suggesting poor calibration of the predicted overall risk across populations. In a subset of models, the net benefit of using the models to inform clinical decisions appeared small and limited to probability thresholds between 5 and 7%. Conclusions The evaluated models had modest predictive performance, with key limitations such as poor calibration (likely due to overfitting in the original development datasets), substantial heterogeneity, and small net benefit across settings. The evidence to support the use of these prediction models for pre-eclampsia in clinical decision-making is limited. Any models that we could not validate should be examined in terms of their predictive performance, net benefit, and heterogeneity across multiple UK settings before consideration for use in practice.

• Dypvik, Johanne; Larsen, Sandra; Haavaldsen, Camilla; Saugstad, Ola Didrik & Eskild, Anne (2020). Placental Weight and Risk of Neonatal Death. JAMA pediatrics. ISSN 2168-6203. 174(2), s. 197–199. doi: 10.1001/jamapediatrics.2019.4556. Fulltekst i vitenarkiv
• Allotey, John; Snell, Kym I.E.; Smuk, Melanie; Hooper, Richard; Chan, Claire & Ahmed, Asif [Vis alle 62 forfattere av denne artikkelen] (2020). Validation and development of models using clinical, biochemical and ultrasound markers for predicting pre-eclampsia: an individual participant data meta-analysis. Health Technology Assessment. ISSN 1366-5278. 24(72), s. 1–290. doi: 10.3310/hta24720. Fulltekst i vitenarkiv Vis sammendrag

  Background: Pre-eclampsia is a leading cause of maternal and perinatal mortality and morbidity. Early identification of women at risk is needed to plan management. Objectives: To assess the performance of existing pre-eclampsia prediction models and to develop and validate models for pre-eclampsia using individual participant data meta-analysis. We also estimated the prognostic value of individual markers. Design: This was an individual participant data meta-analysis of cohort studies. Setting: Source data from secondary and tertiary care. Predictors: We identified predictors from systematic reviews, and prioritised for importance in an international survey. Primary outcomes: Early-onset (delivery at < 34 weeks' gestation), late-onset (delivery at ≥ 34 weeks' gestation) and any-onset pre-eclampsia. Analysis: We externally validated existing prediction models in UK cohorts and reported their performance in terms of discrimination and calibration. We developed and validated 12 new models based on clinical characteristics, clinical characteristics and biochemical markers, and clinical characteristics and ultrasound markers in the first and second trimesters. We summarised the data set-specific performance of each model using a random-effects meta-analysis. Discrimination was considered promising for C-statistics of ≥ 0.7, and calibration was considered good if the slope was near 1 and calibration-in-the-large was near 0. Heterogeneity was quantified using I 2 and τ2. A decision curve analysis was undertaken to determine the clinical utility (net benefit) of the models. We reported the unadjusted prognostic value of individual predictors for pre-eclampsia as odds ratios with 95% confidence and prediction intervals. Results: The International Prediction of Pregnancy Complications network comprised 78 studies (3,570,993 singleton pregnancies) identified from systematic reviews of tests to predict pre-eclampsia. Twenty-four of the 131 published prediction models could be validated in 11 UK cohorts. Summary C-statistics were between 0.6 and 0.7 for most models, and calibration was generally poor owing to large between-study heterogeneity, suggesting model overfitting. The clinical utility of the models varied between showing net harm to showing minimal or no net benefit. The average discrimination for IPPIC models ranged between 0.68 and 0.83. This was highest for the second-trimester clinical characteristics and biochemical markers model to predict early-onset pre-eclampsia, and lowest for the first-trimester clinical characteristics models to predict any pre-eclampsia. Calibration performance was heterogeneous across studies. Net benefit was observed for International Prediction of Pregnancy Complications first and second-trimester clinical characteristics and clinical characteristics and biochemical markers models predicting any pre-eclampsia, when validated in singleton nulliparous women managed in the UK NHS. History of hypertension, parity, smoking, mode of conception, placental growth factor and uterine artery pulsatility index had the strongest unadjusted associations with pre-eclampsia. Limitations: Variations in study population characteristics, type of predictors reported, too few events in some validation cohorts and the type of measurements contributed to heterogeneity in performance of the International Prediction of Pregnancy Complications models. Some published models were not validated because model predictors were unavailable in the individual participant data. Conclusion: For models that could be validated, predictive performance was generally poor across data sets. Although the International Prediction of Pregnancy Complications models show good predictive performance on average, and in the singleton nulliparous population, heterogeneity in calibration performance is likely across settings.

• Haavaldsen, Camilla; Strøm-Roum, Ellen Marie & Eskild, Anne (2019). Temporal changes in fetal death risk in pregnancies with preeclampsia: Does offspring birthweight matter? A population study. European Journal of Obstetrics and Gynecology and Reproductive Biology: X. 2:100009, s. 1–6. doi: 10.1016/j.eurox.2019.100009. Fulltekst i vitenarkiv Vis sammendrag

  Objectives To study the associations of preeclampsia with fetal death risk within percentiles of offspring birthweight, and whether these associations have changed during 1967–2014. Study design In this population study, we included all singleton pregnancies in the Medical Birth Registry of Norway during 1967–2014 (n = 2 607 199). Odds ratios (ORs) for fetal death associated with preeclampsia were estimated within percentiles of birthweight by applying logistic regression analyses. We estimated ORs for the study period as a whole, and for the years 1967–1983 and 1984–2014. Results During the study period as a whole, preeclampsia increased the risk of fetal death, OR 2.73 (95% CI 2.57–2.89), and the fetal death risk associated with preeclampsia differed across percentiles of offspring birthweight. The overall risk of fetal death decreased during our study period, and the decrease was most prominent in preeclamptic pregnancies with low offspring birthweight (<1 percentile). Thus, in recent years, the risk of fetal death in pregnancies with low offspring birthweight was lower in preeclamptic than in non-preeclamptic pregnancies, OR 0.22 (95% CI 0.12-0.41). Only in pregnancies with offspring birthweight within the 10–90 percentiles, the risk of fetal death associated with preeclampsia remained significantly increased throughout the study period. Conclusions The decline in fetal death risk was most prominent in preeclamptic pregnancies with low offspring birthweight. The introduction of a national screening program for preeclampsia in the 1980s, and identification of growth restricted offspring by fetal ultrasonography, may explain our findings.

• Gottschalk, Marthe Sørli; Eskild, Anne; Tanbo, Tom Gunnar & Bjelland, Elisabeth Krefting (2019). Childbirth close to natural menopause: does age at menopause matter? Reproductive Biomedicine Online. ISSN 1472-6483. 39(1), s. 169–175. doi: 10.1016/j.rbmo.2019.03.209. Fulltekst i vitenarkiv Vis sammendrag

  Research question Does a successful spontaneous pregnancy in the years close to natural menopause depend on age at menopause? Design This was a retrospective population-based study of 4157 parous postmenopausal women in Norway, born during the years 1925–1940. Data were obtained by two self-administered questionnaires in the HUNT2 Survey (1995–1997). We calculated the proportions of women who gave birth within 5 years and within 10 years prior to menopause both among all women, and according to categories of age at menopause. Results Overall, 2.7% (114/4157) of all women gave birth within 5 years, and 11.7% (487/4157) gave birth within 10 years, prior to menopause. Among women with menopause before the age of 45 years, 23.5% (81/344) gave birth within 5 years, and 55.5% (191/344) gave birth within 10 years, before menopause. Among the women with menopause at the age of 55 years or older, no women (0/474) gave birth within 5 years, and 0.2% (1/474) gave birth within 10 years, prior to menopause. Conclusions More than half of the women with menopause before the age of 45 years gave birth within the 10 years before natural menopause, whereas virtually no women with menopause at the age of 55 years or older did. Thus, the length of the sterile interval before natural menopause may vary by age at menopause.

• Eskild, Anne; Sommerfelt, Silje; Skau, Irene & Grytten, Jostein Ivar (2019). Offspring birthweight and placental weight in immigrant women from conflict-zone countries; does length of residence in the host country matter? A population study in Norway. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. s. 1–8. doi: 10.1111/aogs.13777. Fulltekst i vitenarkiv Vis sammendrag

  Introduction We aimed to estimate differences in offspring birthweight and placental weight between Norwegian women and immigrants in Norway from countries with armed conflicts. We also studied whether length of residence in Norway was associated with offspring birthweight and placental weight. Material and methods We included in our study all singleton births in Norway at gestational week 28 or beyond during the years 1999‐2014, to mothers who were born in Somalia, Afghanistan, Iraq (total immigrants n = 18 817), or Norway (n = 668 439). Data were obtained from The Medical Birth Registry of Norway and the Central Person Registry of Norway. We estimated the differences between Norwegian and immigrant women in mean offspring birthweight and mean placental weight by applying linear regression analyses. Adjustments were made for maternal age, parity, year of delivery, gestational age at delivery, preeclampsia, and diabetes. Results The immigrant women had 206 g (95% CI 199 to 213 g) lower mean offspring birthweight and 16 g (95% CI 14 to 18 g) lower mean placental weight than Norwegian women. Immigrant women with ≥5 years of residence in Norway had higher offspring birthweight (40 g) and higher placental weight (17 g) than immigrant women with <5 years of residence. Conclusions Immigrant mothers from Somalia, Afghanistan, and Iraq gave birth to infants and placentas with lower weight than Norwegian women. However, the difference between Norwegian women and immigrant women was reduced by length of residence in Norway.

• Bjelland, Elisabeth Krefting; Gran, Jon Michael; Hofvind, Solveig & Eskild, Anne (2019). The association of birthweight with age at natural menopause: a population study of women in Norway. International Journal of Epidemiology. ISSN 0300-5771. 49(2), s. 528–536. doi: 10.1093/ije/dyz207. Fulltekst i vitenarkiv Vis sammendrag

  Background: Previous studies suggest that birthweight may influence age at natural menopause, but the evidence remains inconclusive. Thus, we aimed to estimate the association of birthweight with age at natural menopause. Methods: A retrospective population study of 164 608 women in Norway, aged 48–71years. Data were obtained by two self-administered questionnaires among participants in BreastScreen Norway during 2006–2014. We used Cox proportional hazard models to estimate hazard ratios and logistic regression models to estimate odds ratios of menopause according to birthweight. Restricted cubic splines were applied to allow for possible non-linear associations, and adjustments were made for year and country of birth. Results: Women with birthweight <2500g were median 51years at menopause (interquartile range 49–54years), whereas women with birthweight 3500–3999g were median 52years at menopause (interquartile range 49–54years). The hazard ratio of menopause decreased with increasing birthweight up until 3500g. At birthweights >3500g, we estimated no further decrease (P for non-linearity ¼ 0.007). Birthweight at 2500g increased the odds ratios of menopause before the age of 45 [1.20; 95% confidence interval (CI): 1.14–1.25] and the age of 40 (1.26; 95% CI: 1.15–1.38) compared with birthweight at 3500g. At birthweights 4000g and 4500g, the odds ratio estimates were very similar to the reference group and the CIs overlapped 1.00. Conclusions: We found a non-linear dose-relationship of birthweight with age at natural menopause, and low birthweight was associated with early natural menopause.

• Grytten, Jostein Ivar; Skau, Irene; Sørensen, Rune Jørgen & Eskild, Anne (2018). Does the Use of Diagnostic Technology Reduce Fetal Mortality? Health Services Research (HSR). ISSN 0017-9124. 53(6), s. 4437–4459. doi: 10.1111/1475-6773.12721. Fulltekst i vitenarkiv Vis sammendrag

  Objective: To examine the effect that the introduction of new diagnostic technology in obstetric care has had on fetal death. Data Source The Medical Birth Registry of Norway provided detailed medical information for approximately 1.2 million deliveries from 1967 to 1995. Information about diagnostic technology was collected directly from the maternity units, using a questionnaire. Study Design: The data were analyzed using a hospital fixed‐effects regression with fetal mortality as the outcome measure. The key independent variables were the introduction of ultrasound and electronic fetal monitoring at each maternity ward. Hospital‐specific trends and risk factors of the mother were included as control variables. The richness of the data allowed us to perform several robustness tests. Principal Finding: The introduction of ultrasound caused a significant drop in fetal mortality rate, while the introduction of electronic fetal monitoring had no effect on the rate. In the population as a whole, ultrasound contributed to a reduction in fetal deaths of nearly 20 percent. For post‐term deliveries, the reduction was well over 50 percent. Conclusion: The introduction of ultrasound made a major contribution to the decline in fetal mortality at the end of the last century.

• Tanbo, Tom Gunnar; Zucknick, Manuela & Eskild, Anne (2018). Maternal concentrations of human chorionic gonadotrophin in very early IVF pregnancies and duration of pregnancy: a follow-up study. Reproductive Biomedicine Online. ISSN 1472-6483. 37(2), s. 208–215. doi: 10.1016/j.rbmo.2018.04.048. Fulltekst i vitenarkiv Vis sammendrag

  Research question Are maternal concentrations of human chorionic gonadotropin (HCG) on a fixed day after embryo transfer associated with duration of pregnancy? Design A follow-up study of 1917 singleton pregnancies after IVF was performed. Embryos were cultured for 2 days and maternal HCG concentration quantified on day 12 after embryo transfer. Duration of pregnancy was obtained from the Medical Birth Registry of Norway. Association of HCG concentration (log2-transformed) with duration of pregnancy was estimated as hazard ratios (HR) with 95% confidence intervals (CI) by applying Cox regression proportional hazard models, where time to delivery for pregnancies shortened because of planned Caesarean delivery or induction of labour was treated as censored. Results The estimated median duration of pregnancy from embryo transfer was 266 days (95% CI 266–267 days). Maternal concentration of HCG on day 12 after embryo transfer varied from 1 to 588 IU/l (median 117 IU/l). Duration of pregnancy decreased by increasing HCG concentration, significantly in pregnancies delivered at full term ((257–270 days after embryo transfer; HR 1.127, 95% CI 1.026–1.238, P = 0.012). For each doubling of HCG concentration on day 12 after embryo transfer, duration of pregnancy was shortened by 0.51 days. Adjustment for maternal age, prepregnancy body mass index, being a first-time mother and number of embryos transferred did not change the association. Conclusion High maternal HCG concentration on a fixed day after embryo transfer is likely to indicate early embryo implantation. After embryo transfer, pregnancies with early implantation are shorter than pregnancies with late implantation.

• Eskild, Anne; Monkerud, Lars Chr.; Jukic, Anne Marie Z.; Åsvold, Bjørn Olav & Lie, Kari Helene Elise Kveim (2018). Maternal concentrations of human chorionic gonadotropin (hCG) and risk for cerebral palsy (CP) in the child. A case control study. European Journal of Obstetrics, Gynecology, and Reproductive Biology. ISSN 0301-2115. 228, s. 203–208. doi: 10.1016/j.ejogrb.2018.07.003. Fulltekst i vitenarkiv Vis sammendrag

  Background Intrauterine conditions may be important in the development of cerebral palsy in the child. The hormone, human chorionic gonadotropin (hCG), is synthesized in the placenta, and hCG plays an important role in placental angiogenesis and development. Thus, maternal hCG concentrations may be an indicator of placental function and thereby the intrauterine environment for the offspring. We studied the associations of maternal concentrations of hCG during pregnancy with cerebral palsy in the child. Methods We performed a case-control study nested within a cohort of 29,948 pregnancies in Norway during 1992–1994. Cases were all women within the cohort who gave birth to a singleton child with cerebral palsy diagnosed before five years of age (n = 63). Controls were a random sample of women with a singleton child without cerebral palsy (n = 182). Results The adjusted odds ratio (OR) for cerebral palsyin the child was 0.78 (95% CI: 0.55–1.10) per log-transformed unit of maternal hCG in the 1 st trimester, and the OR was 1.42 (95% CI: 0.94–2.16) in the 2nd trimester. Thus, women who did not have high hCG concentrations in the 1 st trimester and low hCG concentrations in the 2nd trimester, had increased risk for giving birth to a child with cerebral palsy. Adjustments were made for pregnancy week of serum sampling, maternal age and parity.

• Sandvei, Marie Søfteland; Vatten, Lars Johan; Bjelland, Elisabeth Krefting; Eskild, Anne; Hofvind, Solveig & Ursin, Giske [Vis alle 7 forfattere av denne artikkelen] (2018). Menopausal hormone therapy and breast cancer risk: effect modification by body mass through life. European Journal of Epidemiology (EJE). ISSN 0393-2990. doi: 10.1007/s10654-018-0431-7. Fulltekst i vitenarkiv Vis sammendrag

  It is not known whether increased breast cancer risk caused by menopausal hormone therapy (HT) depends on body mass patterns through life. In a prospective study of 483,241 Norwegian women aged 50–69 years at baseline, 7656 women developed breast cancer during follow-up (2006–2013). We combined baseline information on recalled body mass in childhood/adolescence and current (baseline) body mass index (BMI) to construct mutually exclusive life-course body mass patterns. We assessed associations of current HT use with breast cancer risk according to baseline BMI and life-course patterns of body mass, and estimated relative excess risk due to interaction (RERI). Within all levels of baseline BMI, HT use was associated with increased risk. Considering life-course body mass patterns as a single exposure, we used women who “remained at normal weight” through life as the reference, and found that being “overweight as young” was associated with lower risk (hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.76–0.94), whereas women who “gained weight” had higher risk (HR 1.20, 95% CI 1.12–1.28). Compared to never users of HT who were “overweight as young”, HT users who either “remained at normal weight” or “gained weight” in adulthood were at higher risk than expected when adding the separate risks (RERI 0.52, 95% CI 0.09–0.95, and RERI 0.37, 95% CI − 0.07–0.80), suggesting effect modification. Thus, we found that women who remain at normal weight or gain weight in adulthood may be more susceptible to the risk increasing effect of HT compared to women who were overweight as young.

• Bjelland, Elisabeth Krefting; Hofvind, Solveig; Byberg, Liisa & Eskild, Anne (2018). The relation of age at menarche with age at natural menopause: a population study of 336 788 women in Norway. Human Reproduction. ISSN 0268-1161. 33(6), s. 1149–1157. doi: 10.1093/humrep/dey078. Fulltekst i vitenarkiv
• Dypvik, Johanne; Lid, Andrea Johanne; Tanbo, Tom Gunnar & Eskild, Anne (2018). Maternal human chorionic gonadotrophin concentrations in very early pregnancy and risk of hyperemesis gravidarum: A retrospective cohort study of 4372 pregnancies after in vitro fertilization. European Journal of Obstetrics, Gynecology, and Reproductive Biology. ISSN 0301-2115. 221, s. 12–16. doi: 10.1016/j.ejogrb.2017.12.015. Fulltekst i vitenarkiv Vis sammendrag

  Objective We investigated the association of human chorionic gonadotrophin (hCG) concentrations on a fixed day in very early pregnancy with development of hyperemesis gravidarum. Study design This retrospective cohort study included 3107 singleton and 1265 twin pregnancies after in vitro fertilization treated at Department of Reproductive Medicine, Rikshospitalet, Oslo University Hospital, Norway in the period 1996–2013. Maternal serum hCG concentrations was measured on day 12 after embryo transfer. Information about development of hyperemesis gravidarum was obtained by individual linkage to the Medical Birth Registry of Norway. We studied hCG concentrations in very early pregnancy according to development of hyperemesis gravidarum, in singleton and twin pregnancies separately. We estimated the odds ratios for hyperemesis gravidarum with 95% confidence intervals according to quartiles of hCG concentrations. Results In twin pregnancies as compared to singleton pregnancies, we found higher mean maternal hCG concentrations (219 IU/L versus 130 IU/L, p < 0.001 Student’s t-test) and higher prevalence of hyperemesis gravidarum (2.7% versus 1.4%, p = 0.002 chi-squared test). However, both in singleton and in twin pregnancies, we found no significant difference in mean hCG concentrations between women who developed hyperemesis gravidarum and women who did not (Singletons: 122 IU/L versus 130 IU/L, p = 0.504. Twins: 234 IU/L versus 219 IU/L, p = 0.417 Student’s t-test). We found no significant differences in odds ratios for developing hyperemesis gravidarum according to quartiles of hCG concentrations. Conclusions We found no association of maternal hCG concentrations on a fixed day in early pregnancy with development of hyperemesis gravidarum.

• Larsen, Sandra; Haavaldsen, Camilla; Bjelland, Elisabeth Krefting; Dypvik, Johanne; Jukic, Anne Marie & Eskild, Anne (2018). Placental weight and birthweight: The relations with number of daily cigarettes and smoking cessation in pregnancy. A population study. International Journal of Epidemiology. ISSN 0300-5771. 47(4), s. 1141–1150. doi: 10.1093/ije/dyy110. Fulltekst i vitenarkiv
• Hilde, Gunvor; Eskild, Anne; Owe, Katrine Mari; Bø, Kari & Bjelland, Elisabeth Krefting (2017). Exercise in Pregnancy: An Association with Placental Weight? American Journal of Obstetrics and Gynecology. ISSN 0002-9378. 216(2), s. 168.e1–168.e9. doi: 10.1016/j.ajog.2016.10.018. Fulltekst i vitenarkiv Vis sammendrag

  Background: Women with high levels of physical exercise have increased demand for oxygen and nutrients. Thus, in pregnancies of women with high levels of exercise it is conceivable that the supply of oxygen and nutrients to the placenta is sub-optimal, and growth could be impaired. Objective: To study the association of frequency of exercise during pregnancy with placental weight and placental to birthweight ratio. Study design: A prospective study of 80,515 singleton pregnancies in the Norwegian Mother and Child Cohort Study. Frequency of exercise was self-reported by a questionnaire at pregnancy weeks 17 and 30. Information on placental weight and birthweight was obtained by linkage to the Medical Birth Registry of Norway. Results: Placental weight decreased with increasing frequency of exercise (tests for trend, P<0.001). For non-exercisers in pregnancy week 17, crude mean placental weight was 686.1 g compared to 667.3 g in women exercising ≥ 6 times weekly (difference 18.8 g; 95% CI: 12.0 to 25.5). Likewise, in non-exercisers in pregnancy week 30, crude mean placental weight was 684.9 g compared to 661.6 g in women exercising ≥ 6 times weekly (difference 23.3 g; 95% CI: 14.9 to 31.6). The largest difference in crude mean placental weight were seen between non-exercisers at both time points and women exercising ≥ 6 times weekly at both time points (difference 31.7 g; 95% CI: 19.2 to 44.2). Frequency of exercise was not associated with placental to birthweight ratio. Conclusion: We found decreasing placental weight with increasing frequency of exercise in pregnancy. The difference in placental weight between non-exercisers and women with exercising ≥ 6 times weekly was small, and may have no clinical implications.

• Sørensen, Ingvild M.; Joner, Geir; Jenum, Pål; Eskild, Anne; Dahl, Sandra Rinne & Stene, Lars Christian (2017). Maternal serum calcitriol during pregnancy and risk of childhood onset type 1 diabetes. Acta Diabetologica. ISSN 0940-5429. 54, s. 1143–1145. doi: 10.1007/s00592-017-1045-3. Fulltekst i vitenarkiv
• Dypvik, Johanne; Larsen, Sandra; Haavaldsen, Camilla; Jukic, Anne M; Vatten, Lars Johan & Eskild, Anne (2017). Placental weight in the first pregnancy and risk for preeclampsia in the second pregnancy: A population-based study of 186 859 women. European Journal of Obstetrics, Gynecology, and Reproductive Biology. ISSN 0301-2115. 214, s. 184–189. doi: 10.1016/j.ejogrb.2017.05.010. Fulltekst i vitenarkiv Vis sammendrag

  Objective To study whether placental weight in the first pregnancy is associated with preeclampsia in the second pregnancy. Study design In this population-based study, we included all women with two consecutive singleton pregnancies reported to the Medical Birth Registry of Norway during 1999–2012 (n = 186 859). Placental weight in the first pregnancy was calculated as z-scores, and the distribution was divided into five groups of equal size (quintiles). We estimated crude and adjusted odds ratios with 95% confidence intervals for preeclampsia in the second pregnancy according to quintiles of placental weight z-scores in the first pregnancy. The 3rd quintile was used as the reference group. Results Among women without preeclampsia in the first pregnancy, 1.4% (2507/177 149) developed preeclampsia in the second pregnancy. In these women, the risk for preeclampsia in the second pregnancy was associated with placental weight in the first pregnancy in both lowest (crude odds ratio (cOR) 1.30, 95% confidence interval (CI); 1.14–1.47) and highest quintile (cOR 1.20, 95% CI; 1.06–1.36). The risk associated with the highest quintile of placental weight was confined to term preeclampsia. Among women with preeclampsia in the first pregnancy, 15.7% (1522/9710) developed recurrent preeclampsia, and the risk for recurrent preeclampsia was associated with placental weight in lowest quintile in the first pregnancy (cOR 1.30, 95% CI; 1.10–1.55). Adjustment for interval between pregnancies, maternal diabetes, age, and smoking in the first pregnancy did not alter these estimates notably. Conclusion Placental weight in the first pregnancy might help to identify women who could be at risk for developing preeclampsia in a second pregnancy.

• Strøm-Roum, Ellen Marie; Tanbo, Tom Gunnar & Eskild, Anne (2016). The associations of maternal body mass index with birthweight and placental weight. Does maternal diabetes matter? A population study of 106 191 pregnancies. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 95(10), s. 1162–1170. doi: 10.1111/aogs.12947. Fulltekst i vitenarkiv
• Larsen, Sandra; Bjelland, Elisabeth Krefting; Haavaldsen, Camilla & Eskild, Anne (2016). Placental weight in pregnancies with high or low hemoglobin concentrations. European Journal of Obstetrics, Gynecology, and Reproductive Biology. ISSN 0301-2115. 206, s. 48–52. doi: 10.1016/j.ejogrb.2016.08.039. Fulltekst i vitenarkiv Vis sammendrag

  Objectives To study the associations of maternal hemoglobin concentrations with placental weight and placental to birthweight ratio. Study design In this retrospective cohort study, we included all singleton pregnancies during the years 1998–2013 at a large public hospital in Norway (n = 57 062). We compared mean placental weight and placental to birthweight ratio according to maternal hemoglobin concentrations: <9 g/dl, 9–13.5 g/dl or >13.5 g/dl. The associations of maternal hemoglobin concentrations with placental weight and placental to birthweight ratio were estimated by linear regression analyses, and adjustments were made for gestational age at birth, preeclampsia, parity, maternal age, diabetes, body mass index, smoking, offspring sex and year of birth. Results In pregnancies with maternal hemoglobin concentrations <9 g/dl, mean placental weight was 701.2 g (SD 160.6 g), followed by 678.1 g (SD 150.2 g) for hemoglobin concentrations 9–13.5 g/dl and 655.5 g (SD 147.7 g) for hemoglobin concentrations >13.5 g/dl (ANOVA, p < 0.001). Mean placental to birthweight ratio was highest in pregnancies with maternal hemoglobin concentrations <9 g/dl (0.203 (SD 0.036)). We found no difference in mean placental to birthweight ratio for maternal hemoglobin concentrations 9–13.5 g/dl (0.193 (SD 0.040)) and >13.5 g/dl (0.193 (SD 0.043)). Adjustments for our study factors did not alter the estimates notably. Conclusions Placental weight decreased with increasing maternal hemoglobin concentrations. The high placental to birthweight ratio with low maternal hemoglobin concentrations suggests differences in placental growth relative to fetal growth across maternal hemoglobin concentrations.

• Grytten, Jostein Ivar; Monkerud, Lars Chr.; Skau, Irene; Eskild, Anne; Sørensen, Rune Jørgen & Saugstad, Ola Didrik (2016). Saving Newborn Babies – The Benefits of Interventions in Neonatal Care in Norway over More Than 40 Years. Health Economics. ISSN 1057-9230. 26(3), s. 352–370. doi: 10.1002/hec.3314. Fulltekst i vitenarkiv Vis sammendrag

  The aim of this study was to examine the effect that the introduction of new medical interventions at birth has had on mortality among newborn babies in Norway during the period 1967–2011. During this period, there has been a significant decline in mortality, in particular for low birth weight infants. We identified four interventions that together explained about 50% of the decline in early neonatal and infant mortality: ventilators, antenatal steroids, surfactant and insure. The analyses were performed on a large set of data, encompassing more than 1.6 million deliveries (Medical Birth Registry of Norway). The richness of the data allowed us to perform several robustness tests. Our study indicates that the introduction of new medical interventions has been a very important channel through which the decline in mortality among newborn babies occurred during the second half of the last century.

• Dypvik, Johanne; Strøm-Roum, Ellen Marie; Haavaldsen, Camilla; Vatten, Lars Johan & Eskild, Anne (2016). Preeclampsia in pregnancies with and without diabetes: the associations with placental weight. A population study of 655 842 pregnancies. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 95(2), s. 217–224. doi: 10.1111/aogs.12795. Fulltekst i vitenarkiv
• Sørensen, Ingvild M.; Joner, Geir; Jenum, Pål; Eskild, Anne; Brunborg, Cathrine & Torjesen, Peter A [Vis alle 7 forfattere av denne artikkelen] (2016). Vitamin D-binding protein and 25-hydroxyvitamin D during pregnancy in mothers whose children later developed type 1 diabetes. Diabetes/Metabolism Research and Reviews. ISSN 1520-7552. 32(8), s. 883–890. doi: 10.1002/dmrr.2812. Fulltekst i vitenarkiv
• Larsen, Sandra; Dobbin, Joanna; McCallion, Oliver & Eskild, Anne (2016). Intrauterine fetal death and risk of shoulder dystocia at delivery. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 95(12), s. 1345–1351. doi: 10.1111/aogs.13033. Fulltekst i vitenarkiv Vis sammendrag

  Introduction Vaginal delivery is recommended after intrauterine fetal death. However, little is known about the risk of shoulder dystocia in these deliveries. We studied whether intrauterine fetal death increases the risk of shoulder dystocia at delivery. Material and methods In this population-based register study using the Medical Birth Registry of Norway, we included all singleton pregnancies with vaginal delivery of offspring in cephalic presentation in Norway during the period 1967–2012 (n = 2 266 118). Risk of shoulder dystocia was estimated as absolute risk (%) and odds ratio with 95% confidence interval. Adjustment was made for offspring birthweight (in grams). We performed sub-analyses within categories of birthweight (<4000 and ≥4000 g) and in pregnancies with maternal diabetes. Results Shoulder dystocia occurred in 1.1% of pregnancies with intrauterine fetal death and in 0.8% of pregnancies without intrauterine fetal death (p < 0.0001) (crude odds ratio 1.5, 95% confidence interval 1.2–4.9). After adjustment for birthweight, the odds ratio was 5.9 (95% confidence interval 4.7–7.4). In pregnancies with birthweight ≥4000 g, shoulder dystocia occurred in 14.6% of pregnancies with intrauterine fetal death and in 2.8% of pregnancies without intrauterine fetal death (p < 0.001) (crude odds ratio 5.9, 95% confidence interval 4.5–7.9). In pregnancies with birthweight ≥4000 g and concurrent maternal diabetes, shoulder dystocia occurred in 57.1% of pregnancies with intrauterine fetal death and 9.6% of pregnancies without intrauterine fetal death (p < 0.001) (crude odds ratio 12.6, 95% confidence interval 5.9–26.9). Conclusions Intrauterine fetal death increased the risk of shoulder dystocia at delivery, and the absolute risk of shoulder dystocia was particularly high if offspring birthweight was high and the mother had diabetes.

• Eskild, Anne; Herdlevær, Ida Erdal; Strøm-Roum, Ellen Marie; Monkerud, Lars Christian & Grytten, Jostein Ivar (2016). Childbirth or termination of pregnancy: Does paid employment matter? A population study of women in reproductive age in Norway. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 95(5), s. 513–518. doi: 10.1111/aogs.12867. Fulltekst i vitenarkiv
• Strøm-Roum, Ellen Marie; Lid, Julie & Eskild, Anne (2016). Use of contraception among women who request first trimester pregnancy termination in Norway. Contraception. ISSN 0010-7824. 94(2), s. 181–186. doi: 10.1016/j.contraception.2016.04.005. Fulltekst i vitenarkiv
• Tanbo, Tom Gunnar & Eskild, Anne (2015). Maternal hCG concentrations in early IVF pregnancies: associations with number of cells in the Day 2 embryo and oocytes retrieved. Human Reproduction. ISSN 0268-1161. 30(12), s. 2758–2763. doi: 10.1093/humrep/dev269. Fulltekst i vitenarkiv
• Naimy, Zainab; Grytten, Jostein Ivar; Monkerud, Lars Christian & Eskild, Anne (2015). The prevalence of pre-eclampsia in migrant relative to native Norwegian women: A population-based study. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. 122(6), s. 859–865. doi: 10.1111/1471-0528.12978. Fulltekst i vitenarkiv
• Lindemann, Kristina; Småstuen, Milada Cvancarova & Eskild, Anne (2015). Body mass index, diabetes and survival after diagnosis of endometrial cancer: A report from the HUNT-Survey. Gynecologic Oncology. ISSN 0090-8258. 139(3), s. 476–480. doi: 10.1016/j.ygyno.2015.09.088. Fulltekst i vitenarkiv
• Strand, Kristin Melheim; Andersen, Guro Lillemoen; Haavaldsen, Camilla; Vik, Torstein & Eskild, Anne (2015). Association of placental weight with cerebral palsy: population-based cohort study in Norway. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. 123(13), s. 2131–2138. doi: 10.1111/1471-0528.13827. Fulltekst i vitenarkiv
• Justad-Berg, Ragnhild Therese; Eskild, Anne & Strøm-Roum, Ellen Marie (2015). Characteristics of women with repeat termination of pregnancy: A study of all requests for pregnancy termination in Norway during 2007-2011. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 94(11), s. 1175–1180. doi: 10.1111/aogs.12714. Fulltekst i vitenarkiv
• Eskild, Anne; Haavaldsen, Camilla & Vatten, Lars Johan (2014). Placental weight and placental weight to birthweight ratio in relation to Apgar score at birth: A population study of 522 360 singleton pregnancies. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 93(12), s. 1302–1308. doi: 10.1111/aogs.12509. Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Wilkosz, Pawel; Tanbo, Tom Gunnar & Eskild, Anne (2014). Is unilateral oophorectomy associated with age at menopause? A population study (the HUNT2 survey). Human Reproduction. ISSN 0268-1161. 29(4), s. 835–841. doi: 10.1093/humrep/deu026. Fulltekst i vitenarkiv
• Øverland, Eva Astrid; Vatten, Lars Johan & Eskild, Anne (2014). Pregnancy week at delivery and the risk of shoulder dystocia: a population study of 2 014 956 deliveries. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. 121(1), s. 34–41. doi: 10.1111/1471-0528.12427. Fulltekst i vitenarkiv
• Haavaldsen, Camilla; Fedorcsak, Peter; Tanbo, Tom Gunnar & Eskild, Anne (2014). Maternal age and serum concentration of human chorionic gonadotropin in early pregnancy. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 93(12), s. 1290–1294. doi: 10.1111/aogs.12471. Fulltekst i vitenarkiv
• Åsvold, Bjørn Olav; Vatten, Lars Johan; Tanbo, Tom Gunnar & Eskild, Anne (2014). Concentrations of human chorionic gonadotrophin in very early pregnancy and subsequent pre-eclampsia: A cohort study. Human Reproduction. ISSN 0268-1161. 29(6), s. 1153–1160. doi: 10.1093/humrep/deu068. Fulltekst i vitenarkiv
• Åsvold, Bjørn Olav; Eskild, Anne & Vatten, Lars Johan (2014). Human chorionic gonadotropin, angiogenic factors, and preeclampsia risk: A nested case-control study. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 93(5), s. 454–462. doi: 10.1111/aogs.12363. Fulltekst i vitenarkiv

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• Kulseng, Carl Petter Skaar; Sommerfelt, Silje; Flo, Kari; Gjesdal, Kjell Inge; Peterson, Helene Fjeldvik & Hillestad, Vigdis [Vis alle 7 forfattere av denne artikkelen] (2025). Corrigendum to “Placental size at gestational week 27 and 37: The associations with pulsatility index in the uterine and the fetal-placental arteries” [Placenta 145C (2024) 45-50, (S0143400423006100), (10.1016/j.placenta.2023.11.014)]. Placenta. ISSN 0143-4004. 164, s. 49–49. doi: 10.1016/j.placenta.2025.03.011. Fulltekst i vitenarkiv
• Sagberg, Karianne; Lie, Torgrim; Peterson, Helene Fjeldvik; Hillestad, Vigdis; Eskild, Anne & Bø, Lars Eirik (2024). EP01.13: A new method for placental volume measurements using tracked two-dimensional ultrasound and automatic image segmentation. Ultrasound in Obstetrics and Gynecology. ISSN 0960-7692. 64(S1), s. 110–110. doi: 10.1002/uog.28028. Fulltekst i vitenarkiv
• Langås, Julie Røgler; Eskild, Anne; Hofvind, Solveig Sand-Hanssen & Bjelland, Elisabeth Krefting (2024). The association of adolescent to midlife weight change with age at natural menopause: a population study of 263,586 women in Norway. Norsk Epidemiologi, Supplement. ISSN 0803-4206. 32(Supplement 1), s. 61–61. doi: 10.5324/nje.v32i1.6006. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: A high body mass index (BMI) has been associated with later menopause, whereas a low BMI has been associated with earlier menopause in previous studies. Also changes in body weight across the life course may influence age at menopause, although the evidence remains inconclusive. Aim: To study the association of adolescent to midlife weight change with age at natural menopause. Methods: We performed a retrospective population-based cohort study of 263 586 women aged 50-69 years attending the Norwegian breast cancer screening program (BreastScreen Norway). During the years 2006 to 2015, all participants were invited to fill in two self-administered questionnaires. The associations of adolescent to midlife weight change with age at menopause were estimated as hazard ratios (HR) using Cox proportional hazard models. We included nine categories of weight change based on recalls of adolescent weight compared to peers and quartiles of midlife weight in kilograms. The nine weight change categories were: stable low, stable average (reference), stable high, average to low, high to average, high to low, average to high, low to average, and low to high weight. We adjusted for year and country of birth, education, number of childbirths, height, smoking, and exercise. Results: Median age at menopause was 52 years (IQR 49-54 years). Women with the largest weight loss had the highest HR of reaching menopause (adjusted HR 1.11, 95% CI: 1.06-1.17), compared to women with a stable average weight. Conversely, women with the largest weight gain had a lower hazard (adjusted HR 0.96, 95% CI: 0.93-0.99). Women who remained at a stable high weight from adolescence to midlife had the lowest HR of reaching menopause (adjusted HR 0.93, 95% CI: 0.90-0.95). Conclusions: Women with the largest weight loss had the earliest menopause, and women who remained at a high weight from adolescence to midlife had the latest menopause. Our findings suggest that weight change from adolescence to midlife may influence the timing of menopause.

• Langås, Julie Røgler; Hofvind, Solveig Sand-Hanssen; Støer, Nathalie Charlotte; Eskild, Anne & Bjelland, Elisabeth Krefting (2024). Adolescent to midlife exercise trajectories and age at menopause: a population study of 246 147 women in Norway. Norsk Epidemiologi, Supplement. ISSN 0803-4206. 32(Supplement 1), s. 42–42. doi: 10.5324/nje.v32i1.6006. Fulltekst i vitenarkiv
• Eskild, Anne (2024). Kort avstand mellom svangerskapene kan være bra. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 144(13). doi: 10.4045/tidsskr.24.0460. Fulltekst i vitenarkiv
• Kulseng, Carl Petter Skaar; Sommerfelt, Silje; Flo, Kari; Gjesdal, Kjell Inge; Peterson, Helene Fjeldvik & Hillestad, Vigdis [Vis alle 8 forfattere av denne artikkelen] (2024). Abstracts of the 34th World Congress on Ultrasound in Obstetrics and Gynecology, 15-18 September 2024, Budapest, Hungary. Ultrasound in Obstetrics and Gynecology. ISSN 0960-7692. 64(S1), s. 277–278. doi: 10.1002/uog.28717. Fulltekst i vitenarkiv
• Haavaldsen, Camilla & Eskild, Anne (2024). Abstracts of the 34th World Congress on Ultrasound in Obstetrics and Gynecology, 15-18 September 2024, Budapest, Hungary. Ultrasound in Obstetrics and Gynecology. ISSN 0960-7692. 64, s. 34–35. doi: 10.1002/uog.27812. Fulltekst i vitenarkiv
• Langås, Julie Røgler; Eskild, Anne; Hofvind, Solveig Sand-Hanssen & Bjelland, Elisabeth Krefting (2023). The dose–response relationship of pre-menopausal alcohol consumption with age at menopause: a population study of 280 497 women in Norway. Fulltekst i vitenarkiv
• Riise, Hilde Kristin Refvik; Igland, Jannicke; Sulo, Gerhard; Iversen, Marjolein M.; Graue, Marit & Eskild, Anne [Vis alle 8 forfattere av denne artikkelen] (2022). Cardiovascular disease in women with preeclampsia who give birth to infants with very low or very high birthweight – a national cohort study (1980-2009). Fulltekst i vitenarkiv
• Blix, Ellen; Eskild, Anne; Schau, Irene & Grytten, Jostein Ivar (2022). The impact of the introduction of intrapartum fetal ECG ST segment analysis. A population study. Fulltekst i vitenarkiv
• Langås, Julie Røgler; Eskild, Anne; Hofvind, Solveig Sand-Hanssen & Bjelland, Elisabeth Krefting (2022). The dose-response relationship of premenopausal alcohol consumption with age at menopause: a population study of 280,497 women in Norway. Fulltekst i vitenarkiv
• Lie, Torgrim; Sagberg, Karianne; Peterson, Helene Fjeldvik; Hillestad, Vigdis; Eskild, Anne & Bø, Lars Eirik (2022). Placental volume measurements using tracked 2D ultrasound. Fulltekst i vitenarkiv
• Grytten, Jostein Ivar; Blix, Ellen; Skau, Irene & Eskild, Anne (2022). STAN and fetal deaths. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 101(12), s. 1460–1461. doi: 10.1111/aogs.14472. Fulltekst i vitenarkiv
• Gottschalk, Marthe Sørli; Eskild, Anne; Hofvind, Solveig & Bjelland, Elisabeth Krefting (2021). The association of number of childbirths with age at menopause: A population study of women in Norway. Fulltekst i vitenarkiv
• Eskild, Anne; Skau, Irene; Haavaldsen, Camilla & Grytten, Jostein Ivar (2021). Ultralyd redder fosterliv. 141(10). doi: 10.4045/tidsskr.21.0256. Fulltekst i vitenarkiv
• Haavaldsen, Camilla; Morken, Nils-Halvdan & Eskild, Anne (2021). Antall induksjoner øker – har det noen betydning for utfallet? Fulltekst i vitenarkiv
• Haavaldsen, Camilla; Morken, Nils-Halvdan & Eskild, Anne (2021). Increasing prevalence of labour induction; has it had any impact on the prevalence of adverse pregnancy outcomes? A populations study in Norway 1999-2019. Fulltekst i vitenarkiv
• Dypvik, Johanne; Saugstad, Ola Didrik & Eskild, Anne (2020). More details needed on association of placental weight with risk of neonatal death - Reply. JAMA pediatrics. ISSN 2168-6203. 174(9), s. 905–906. doi: 10.1001/jamapediatrics.2020.0975. Fulltekst i vitenarkiv
• Gottschalk, Marthe Sørli; Eskild, Anne; Hofvind, Solveig; Gran, Jon Michael & Bjelland, Elisabeth Krefting (2020). Reply: Menarche age, menopausal age and cumulative exposure to endogenous estrogens. Human Reproduction. ISSN 0268-1161. doi: 10.1093/humrep/deaa276. Fulltekst i vitenarkiv
• Blix, Ellen; Eskild, Anne; Skau, Irene & Grytten, Jostein Ivar (2019). Har innføringen av STAN-teknologien i Norge ført til færre dødfødsler, dødsfall hos nyfødte eller at færre barn blir født med lav apgar-skår? En populasjonstudie. Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Gran, Jon Michael; Hofvind, Solveig & Eskild, Anne (2019). The association of birthweight with age at natural menopause. A population study of women in Norway. Fulltekst i vitenarkiv
• Gottschalk, Marthe Sørli; Eskild, Anne; Hofvind, Solveig; Gran, Jon Michael & Bjelland, Elisabeth Krefting (2019). Temporal trends in age at menarche and age at menopause: a population study of 312 656 women in Norway. Norsk Epidemiologi, Supplement. ISSN 0803-4206. 28, s. 77–77. Fulltekst i vitenarkiv
• Gottschalk, Marthe Sørli; Eskild, Anne; Hofvind, Solveig; Gran, Jon Michael & Bjelland, Elisabeth Krefting (2019). Temporal trends in age at menarche and age at menopause: a population study of 312 656 women in Norway. Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Gran, Jon Michael; Hofvind, Solveig & Eskild, Anne (2019). The association of birthweight with age at natural menopause. A population study of women in Norway. Norsk Epidemiologi, Supplement. ISSN 0803-4206. 28, s. 78–78. Fulltekst i vitenarkiv
• Eskild, Anne; Klovning, Atle; Swensen, Elisabeth & Salvesen, Kjell Å (2019). Glukosebelastningstesting av de fleste gravide er en dårlig ide. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 139(2), s. 131–131. doi: 10.4045/tidsskr.18.0898. Fulltekst i vitenarkiv
• Larsen, Sandra; Haavaldsen, Camilla; Bjelland, Elisabeth Krefting; Dypvik, Johanne; Jukic, Anne Marie & Eskild, Anne (2018). Placental weight and birthweight; the relations with number of daily cigarettes and smoking cessation in pregnancy. A population study. Norsk Epidemiologi, Supplement. ISSN 0803-4206. Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Hofvind, Solveig; Byberg, Liisa & Eskild, Anne (2018). The relation of age at menarche with age at menopause: a population study of 336 788 women in Norway. Fulltekst i vitenarkiv
• Eskild, Anne (2018). Who should be in a position to provide pregnancy terminations? Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. doi: 10.4045/tidsskr.18.0304. Fulltekst i vitenarkiv
• Eskild, Anne (2018). Hvem skal kunne tilby svangerskapsavbrudd? Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 138(9), s. 796–796. doi: 10.4045/tidsskr.18.0304. Fulltekst i vitenarkiv
• Sandvei, Marie Søfteland; Vatten, Lars Johan; Bjelland, Elisabeth Krefting; Eskild, Anne; Hofvind, Solveig & Ursin, Giske [Vis alle 7 forfattere av denne artikkelen] (2018). Menopausal hormone therapy and breast cancer risk: effect modification by body mass through life. Fulltekst i vitenarkiv
• Gottschalk, Marthe Sørli; Eskild, Anne; Tanbo, Tom Gunnar & Bjelland, Elisabeth Krefting (2018). Childbirth close to natural menopause: does age at menopause matter? Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Hofvind, Solveig; Byberg, Liisa & Eskild, Anne (2017). The relation of age at menarche with age at menopause: a population study of 336 788 women in Norway. Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Hofvind, Solveig; Byberg, Liisa & Eskild, Anne (2017). The relation of age at menarche with age at menopause: a population study of 336 788 women in Norway. Norsk Epidemiologi, Supplement. ISSN 0803-4206. Fulltekst i vitenarkiv
• Haavaldsen, Camilla; Fedorcsák, Péter; Tanbo, Tom Gunnar & Eskild, Anne (2015). Reply to Bang Hyun Lee et al.: Maternal age and human chorionic gonadotropin in early pregnancy: Influence of gonadotropin-releasing hormone. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 94(4), s. 444–444. doi: 10.1111/aogs.12583. Fulltekst i vitenarkiv
• Strand, Kristin Melheim; Andersen, Guro Lillemoen; Vik, Torstein & Eskild, Anne (2015). Is placental weight and placental weight relative to the infant size at birth associated with risk of cerebral palsy? Developmental Medicine & Child Neurology. ISSN 0012-1622. 57. doi: 10.1111/dmcn.35_12887. Fulltekst i vitenarkiv
• Strand, Kristin Melheim; Andersen, Guro Lillemoen; Vik, Torstein & Eskild, Anne (2015). Is placental weight and placental weight relative to the infant size at birth associated with risk of cerebral palsy? Fulltekst i vitenarkiv
• Bjelland, Elisabeth Krefting; Wilkosz, Pawel; Tanbo, Tom Gunnar & Eskild, Anne (2014). Is unilateral oophorectomy associated with age at menopause? A population study. Fulltekst i vitenarkiv

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