Camilla Haavaldsen

• 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), p. 155–161. doi: 10.1002/uog.70160. Full text in Research Archive
• 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), p. 905–914. doi: 10.1007/s10654-024-01148-y. Full text in Research Archive Show summary

  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, p. 7–12. doi: 10.1016/j.placenta.2024.02.010. Full text in Research Archive Show summary

  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.

• 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, p. 38–44. doi: 10.1016/j.placenta.2023.11.003. Full text in Research Archive Show summary

  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.

• Sheikh, Jameela; Allotey, John; Kew, Tania; Fernández-Félix, Borja M.; Zamora, Javier & Khalil, Asma [Show all 50 contributors for this article] (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), p. 2049–2062. doi: 10.1016/S0140-6736(22)01191-6. Full text in Research Archive Show summary

  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.

• 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. p. 1–16. doi: 10.1111/aogs.14489. Full text in Research Archive Show summary

  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.

• 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. Full text in Research Archive
• Snell, Kym I.E.; Allotey, John; Smuk, Melanie; Hooper, Richard; Chan, Claire & Ahmed, Asif [Show all 60 contributors for this article] (2020). External validation of prognostic models predicting pre-eclampsia: individual participant data meta-analysis. BMC Medicine. 18, p. 1–18. doi: 10.1186/s12916-020-01766-9. Full text in Research Archive Show summary

  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), p. 197–199. doi: 10.1001/jamapediatrics.2019.4556. Full text in Research Archive
• Allotey, John; Snell, Kym I.E.; Smuk, Melanie; Hooper, Richard; Chan, Claire & Ahmed, Asif [Show all 62 contributors for this article] (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), p. 1–290. doi: 10.3310/hta24720. Full text in Research Archive Show summary

  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, p. 1–6. doi: 10.1016/j.eurox.2019.100009. Full text in Research Archive Show summary

  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.

• 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), p. 1141–1150. doi: 10.1093/ije/dyy110. Full text in Research Archive
• 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, p. 184–189. doi: 10.1016/j.ejogrb.2017.05.010. Full text in Research Archive Show summary

  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.

• 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, p. 48–52. doi: 10.1016/j.ejogrb.2016.08.039. Full text in Research Archive Show summary

  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.

• 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), p. 217–224. doi: 10.1111/aogs.12795. Full text in Research Archive
• 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), p. 2131–2138. doi: 10.1111/1471-0528.13827. Full text in Research Archive
• Oostwaard, Miriam F Van; Langenveld, Josje; Schuit, Ewoud; Papatsonis, Dimitri NM; Brown, Mark A & Byaruhanga, Romano N [Show all 29 contributors for this article] (2015). Recurrence of hypertensive disorders of pregnancy: An individual patient data metaanalysis. American Journal of Obstetrics and Gynecology. ISSN 0002-9378. 212(5), p. 624.e1–624.e17. doi: 10.1016/j.ajog.2015.01.009. Full text in Research Archive
• 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), p. 1302–1308. doi: 10.1111/aogs.12509. Full text in Research Archive
• 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), p. 1290–1294. doi: 10.1111/aogs.12471. Full text in Research Archive
• Strøm-Roum, Ellen Marie; Haavaldsen, Camilla; Tanbo, Tom Gunnar & Eskild, Anne (2013). Paternal age, placental weight and placental to birthweight ratio: a population-based study of 590 835 pregnancies. Human Reproduction. ISSN 0268-1161. 28(11), p. 3126–3133. doi: 10.1093/humrep/det299. Full text in Research Archive
• Strøm-Roum, Ellen Marie; Haavaldsen, Camilla; Tanbo, Tom Gunnar & Eskild, Anne (2013). Placental weight relative to birthweight in pregnancies with maternal diabetes mellitus. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 92(7), p. 783–789. doi: 10.1111/aogs.12104. Full text in Research Archive
• Haavaldsen, Camilla; Samuelsen, Sven Ove & Eskild, Anne (2013). Fetal death and placental weight/birthweight ratio: a population study. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 92(5), p. 583–590. doi: 10.1111/aogs.12105. Full text in Research Archive
• Haavaldsen, Camilla; Tanbo, Tom Gunnar & Eskild, Anne (2012). Placental weight in singleton pregnancies with and without assisted reproductive technology: a population study of 536 567 pregnancies. Human Reproduction. ISSN 0268-1161. 27(2), p. 576–582. doi: 10.1093/humrep/der428. Full text in Research Archive
• Haavaldsen, Marit Camilla; Samuelsen, Sven Ove & Eskild, Anne (2011). The association of maternal age with placental weight: a population-based study of 536 954 pregnancies. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. 118(12), p. 1470–1476. doi: 10.1111/j.1471-0528.2011.03053.x. Full text in Research Archive
• Haavaldsen, Marit Camilla; Sarfraz, Aahshi Ambareen; Samuelsen, Sven Ove & Eskild, Anne (2010). The impact of maternal age on fetal death: does length of gestation matter? American Journal of Obstetrics and Gynecology. ISSN 0002-9378. 203(6), p. 554.e1–554.e8. doi: 10.1016/j.ajog.2010.07.014. Full text in Research Archive

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• Sørbye, Ingvil Krarup; Gunnes, Nina; Solhoff, Aslak Vimme; Haavaldsen, Camilla; Kessler, Jørg & Kjøllesdal, Anne M [Show all 14 contributors for this article] (2025). Multicentre double-blind randomised placebo-controlled four-arm trial to assess the effect of oral sodium bicarbonate and intravenous hyoscine butylbromide on spontaneous delivery after induction of labour in nulliparous women: Protocol for the Safe Induction of Labour Trial (SAINT). doi: 10.1136/bmjopen-2024-093992. Full text in Research Archive
• 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, p. 34–35. doi: 10.1002/uog.27812. Full text in Research Archive
• Eskild, Anne; Skau, Irene; Haavaldsen, Camilla & Grytten, Jostein Ivar (2021). Ultralyd redder fosterliv. 141(10). doi: 10.4045/tidsskr.21.0256. Full text in Research Archive
• Haavaldsen, Camilla; Morken, Nils-Halvdan & Eskild, Anne (2021). Antall induksjoner øker – har det noen betydning for utfallet? Full text in Research Archive
• Haavaldsen, Camilla (2021). Overtid og induksjon - når indusere ved overtidig svangerskap. Full text in Research Archive
• 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. Full text in Research Archive
• 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. Full text in Research Archive
• 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), p. 444–444. doi: 10.1111/aogs.12583. Full text in Research Archive
• Strøm-Roum, Ellen Marie; Haavaldsen, Camilla; Tanbo, Tom Gunnar & Eskild, Anne (2012). Placental weight relative to birthweight in pregnancies with maternal diabetes mellitus. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 91, p. 130–130. Full text in Research Archive
• Haavaldsen, Camilla; Sarfraz, Aahshi Ambareen; Samuelsen, Sven Ove & Eskild, Anne (2011). The Impact of Maternal Age on Fetal Death: Does Length of Gestation Matter? Obstetrical and Gynecological Survey. ISSN 0029-7828. 66(4), p. 185–186. doi: 10.1097/OGX.0b013e3182114936. Full text in Research Archive
• Haavaldsen, Marit Camilla; Sarfraz, Aahshi Ambareen & Eskild, Anne (2010). Lav fosterdødsrisiko etter termin i Norge. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 130(21), p. 2114–2114. Full text in Research Archive
• Haavaldsen, Camilla (2014). Fetal death: high maternal age at childbirth and the placenta. Universitetet i Oslo. Full text in Research Archive

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