Peter Zoltan Fedorcsak

• Mikkelsen, Thea Falkenberg; Vera-Rodriguez, Maria; Fedorcsák, Zsofia; Greggains, Gareth; Fedorcsak, Peter Zoltan & Hald, Kirsten (2026). Reduced endometrial LIF expression in women with uterine fibroids and its restoration following myomectomy. European Journal of Obstetrics, Gynecology, and Reproductive Biology. ISSN 0301-2115. 326, p. 115340–115340. doi: 10.1016/j.ejogrb.2026.115340. Full text in Research Archive
• Skuland, Trine; Fosslie, Madeleine Lystad; Khodeer, Sherif; Alemu, Endalkachew Ashenafi; Johansen, Jens Vilstrup & Indahl, Marie [Show all 12 contributors for this article] (2025). Broad H3K4me3 domains support oocyte genome silencing and maturation but are dispensable for repression in early embryos. Development. ISSN 0950-1991. 152(21), p. 1–15. doi: 10.1242/dev.204638. Full text in Research Archive Show summary

  Epigenetic reprogramming and embryonic genome activation (EGA) are crucial events during early development. Establishment of distinctive broad histone H3 lysine 4 trimethylation (H3K4me3) domains in the oocyte is necessary for genome silencing, and their removal in the 2-cell embryo is crucial for EGA and development in mice. However, the stage-specific requirement for broad H3K4me3 domains is unclear. Here, we show that inducing broad H3K4me3 removal in mouse oocytes can relieve genome silencing, impair oocyte maturation timing, and may cause transcriptional reactivation in resulting parthenogenetic 1-cell embryos. We further demonstrate that broad H3K4me3 demethylation precedes EGA but, surprisingly, premature depletion in zygotes or early 2-cell embryos does not alter the transcriptional program. Our findings suggest that broad H3K4me3 domains are required for oocyte genome silencing, timely maturation and post-fertilisation silencing, but onward pre-EGA transcriptional repression is not dependent on the original mark. This work contributes to the understanding of events and mechanisms involved in genome silencing and activation in early development, providing insight into potential modes of failure that may contribute to infertility.

• Fosslie, Madeleine Lystad; Ilaslan, Erkut; Skuland, Trine; Choudalakis, Michel; Søegaard, Mirra Louise Cicilie & Halliwell, Jason Alexander [Show all 23 contributors for this article] (2025). Major waves of H2A.Z incorporation during mouse oogenesis and preimplantation embryo development. Nature Communications. 17(1). doi: 10.1038/s41467-025-66919-x. Full text in Research Archive Show summary

  Abstract Epigenomes of mammalian oocytes and embryos undergo major transitions essential for successful development. Here, we provide genome-wide maps of histone variant H2A.Z during twelve stages of mouse oogenesis and preimplantation embryo development and relate it to histone marks and genomic features. This revealed that major waves of H2A.Z incorporation occur early in growing oocytes, forming distinct patterns of maternal, embryonic, and persistent H2A.Z enrichment. Late maternal enrichment is inherited by the zygote and precedes reduced formation of lamina associated domains and early replication in the maternal genome of 2-cell embryos. Persistent H2A.Z enrichment is strongly associated with CpG islands and H3K4me3 near transcription start sites of active genes, but thousands of maternal and embryonic H2A.Z incorporation sites exist elsewhere, frequently at transposable elements. The persisting H2A.Z enrichments across related developmental stages enable preservation of epigenetic information despite major concurrent changes in H3K4me3, H3K27me3, and DNA methylation. Altogether, this advances our understanding of how histone variants contribute to epigenetic reprogramming during mammalian oogenesis and early development.

• Li, Yanjiao; Wang, Yunhao; Cengiz, Aylin; Jin, Kangxuan; castroviejo, Blanca Corral & Lin, Xiaolin [Show all 19 contributors for this article] (2025). The RNA m6A landscape during human oocyte-to-embryo transition. EMBO Journal. ISSN 0261-4189. 44(14), p. 4150–4180. doi: 10.1038/s44318-025-00474-5. Full text in Research Archive Show summary

  RNA N6-methyladenosine (m6A, m6A) modification is a critical regulator for a range of physiological processes. However, the dynamic m6A profiles within human preimplantation embryos remain uncharacterized. Here, we present the first RNA m6A landscape of single human oocytes and early embryos. Comparative analyses with mouse data reveal an intriguing divergence during the window of zygotic genome activation. m6A-modified genes are involved in regulation of gene transcription, while unmodified genes are mainly associated with basic metabolic processes. Maternal decay mRNAs exhibit a propensity for m6A modifications, and these genes are targeted by miRNAs. m6A modified genes that are constantly expressed across all stages demonstrate higher translation efficiency. Moreover, we observe frequent m6A enrichment on stage-specifically expressed retrotransposons, particularly within young subfamilies. m6A inhibitor leads to m6A erasure on massive retrotransposons. In summary, this study provides a resource to broaden our understanding about the regulatory roles of m6A during early human embryo development.

• Fedorcsak, Peter Zoltan (2024). Moderate benefit of escape room game on learning outcome in medicine. BMC Medical Education. 24. doi: 10.1186/s12909-024-06352-8. Full text in Research Archive Show summary

  Background Well-designed escape room games engage students with complex problems and challenge clinical and teamwork skills, but their impact on learning has been uncertain. This study aimed to estimate the effect size of escape room game on performance in a broad knowledge test. Methods During clinical rotation in reproductive endocrinology and infertility (REI), medical students participated in a 3-hour small-group class. For 2 semesters, groups had traditional patient visits and case discussions, and for 3 semesters, patient visits and an escape room game including debrief. The game was set up in the outpatient clinic, the puzzles were taken from clinical problems in REI, and challenges included operating an ultrasound scanner on a mannequin. Mid-semester, students completed a test of general knowledge in REI. To estimate the effect of small group class on declarative knowledge, test scores of students who had already had the class (exposed) were compared to scores of those who had not yet had the class (control). Results Students were highly satisfied with gamified teaching. Those who attended the small group class without the escape room game achieved similar scores on knowledge test than control students (Cohen’s d = 0.05, 95%CI -0.58 to 0.68, n = 71). Students who played the escape room game achieved marginally higher score than respective controls (Cohen’s d = 0.22, 95%CI -0.1 to 0.53, n = 182). Conclusions Escape room game may improve learning outcome of a traditional small group class, but the effect of a single game session on declarative knowledge is modest and is unlikely to exceed related instructional methods like simulation.

• Li, Yanjiao; Wang, Yunhao; Vera-Rodriguez, Maria; Lindeman, Leif Christopher; Skuggen, Linda Ellevog & Rasmussen, Erik Magne Koscielniak [Show all 21 contributors for this article] (2023). Single-cell m6A mapping in vivo using picoMeRIP–seq. Nature Biotechnology. ISSN 1087-0156. doi: 10.1038/s41587-023-01831-7. Full text in Research Archive Show summary

  Abstract Current N 6 -methyladenosine (m 6 A) mapping methods need large amounts of RNA or are limited to cultured cells. Through optimized sample recovery and signal-to-noise ratio, we developed picogram-scale m 6 A RNA immunoprecipitation and sequencing (picoMeRIP–seq) for studying m 6 A in vivo in single cells and scarce cell types using standard laboratory equipment. We benchmark m 6 A mapping on titrations of poly(A) RNA and embryonic stem cells and in single zebrafish zygotes, mouse oocytes and embryos.

• Mikkelsen, Thea Falkenberg; Vera-Rodriguez, Maria; Greggains, Gareth David; Fedorcsak, Peter Zoltan & Hald, Kirsten (2023). Effect of endometrial biopsy method on ribonucleic acid quality and gene expression analysis in patients with leiomyoma. F&S Reports. doi: 10.1016/j.xfre.2023.11.006. Full text in Research Archive
• Kvernflaten, Birgit; Fedorcsak, Peter Zoltan & Solbrække, Kari Nyheim (2022). It’s all about kids, kids, kids! Negotiating reproductive citizenship and patient centered-care in ‘factory IVF’. BioSocieties. ISSN 1745-8552. doi: 10.1057/s41292-021-00268-y. Full text in Research Archive
• Kvernflaten, Birgit; Fedorcsak, Peter Zoltan & Solbrække, Kari Nyheim (2022). Kin or Research Material? Exploring IVF Couples’ Perceptions about the Human Embryo and Implications for Disposition Decisions in Norway. Journal of Bioethical Inquiry. ISSN 1176-7529. doi: 10.1007/s11673-022-10214-7. Full text in Research Archive Show summary

  In vitro fertilization (IVF) involves making embryos outside of the human body, which has spurred debate about the status of the embryo, embryo research and donation. We explore couples’ perceptions about embryos and their thoughts and acceptability about various disposition decisions in Norway. Based on an ethnographic study including interviews and observations in an IVF clinic, we show that couples do not perceive their pre-implantation IVF embryos to be human lives; rather, they consider successful implantation the start of life. We suggest that this response indicates a change in the perception of the human embryo or the fertilised egg from incipient life—a viewpoint that was dominant in the discussions of embryo research in the 1980s and 1990s. We also show how this view of the pre-implantation embryo elucidates why donating embryos to research appears acceptable but donating to other infertile couples seems rather difficult. Before transfer to a woman’s uterus, the embryo exists in a liminality; it is not yet human life but a living cell with potential for both research and pregnancy. When an embryo is implanted and pregnancy is confirmed, human life activates; the embryo becomes potential kin, influencing couples’ struggles with donating embryos to other couples.

• Jørgensen, Hilde; Fedorcsak, Peter Zoltan; Isaacson, Keith; Tevonian, Erin; Xiao, Amy & Beste, Michael [Show all 9 contributors for this article] (2022). Endometrial cytokines in patients with and without endometriosis evaluated for infertility. Fertility and Sterility. ISSN 0015-0282. 117(3), p. 629–640. doi: 10.1016/j.fertnstert.2021.11.024. Full text in Research Archive Show summary

  Objective To evaluate whether endometrial molecular profiles distinguish subsets of patients according to clinical characteristics, and to infer dysregulated immune networks, by measuring cytokines, chemokines, and growth factors in endometrial biopsy specimens from a cohort of infertile women with a high incidence of endometriosis. Design Prospective cohort study. Setting Department of Gynecology at a university hospital. Patient(s) Patients undergoing laparoscopy for infertility assessment (n = 103). Intervention(s) Endometrial biopsies were performed during surgery. Fertility outcome and clinical parameters were registered preoperatively and after 6 months. Main Outcome Measure(s) The concentrations of 48 factors in endometrial biopsy specimens were analyzed with respect to clinical status in univariate and multivariate frameworks.

• Tanbo, Tom Gunnar & Fedorcsak, Peter Zoltan (2021). Can time to menopause be predicted? Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 100, p. 1961–1968. doi: 10.1111/aogs.14253. Full text in Research Archive Show summary

  Menopause represents the definite end of a woman’s reproductive life and the onset of a persistent hypoestrogenic state. This postmenopausal period will for most women last several decades. Although mean menopausal age seems to have increased somewhat during the last century, there is a significant individual variation in age at natural menopause. With efficient contraception, women of reproductive age can now, to some extent, choose when they want to have children. As a consequence of this and other sociodemographic changes, age at first birth has increased significantly over the last 50 years. It is well documented that long before a woman enters the menopausal transition and subsequent menopause, fertility declines and finally ceases. Being able to predict when a woman will enter menopause would therefore, from a reproductive perspective, be of major interest. Several sociodemographic, morphometric, and endocrine factors are associated with age at menopause or time to menopause. Unfortunately the sensitivity and specificity of these in predicting time to or age at menopause are low. Therefore, with the exception of anti-Müllerian hormone measurements, either alone or in combination with chronological age close to menopause, there are as of now no reliable ways of predicting when a woman will enter menopause.

• Schenck, Annejet; Vera-Rodriguez, Maria; Greggains, Gareth; Davidson, Ben & Fedorcsák, Péter (2020). Spatial and temporal changes in follicle distribution in the human ovarian cortex. Reproductive Biomedicine Online. ISSN 1472-6483. 42(2), p. 375–383. doi: 10.1016/j.rbmo.2020.10.013. Full text in Research Archive Show summary

  Research question How does follicle distribution evolve in the human ovarian cortex between the ages of 20 and 35 years? Design Fragments of ovarian cortex from women undergoing unilateral oophorectomy for fertility preservation were obtained for quantitative histological assessment, including recording the two-dimensional coordinates of the follicles. Data were analysed using spatial statistical methods. Results A total of 53 ovarian cortex tissue samples, containing 1–803 follicles each, were obtained from 14 women aged 20–35 years. Primordial and transitory follicles lay in a clustered manner in the human ovarian cortex, with an average cluster radius of around 270 µm (95% confidence interval 154–377 µm; n = 49). Follicle density declined with age (P = 0.006, n = 13), and the distance from the nearest neighbouring follicle increased (P = 0.004, n = 13). Cluster radius decreased with age (P = 0.02, n = 13), but the degree of clustering tended to increase (P = 0.11, n = 13). In the majority of the samples, follicles at different stages lay in different clusters (P < 0.05, n = 13). Conclusions This study shows that primordial and transitory follicles lie in different clusters in the human ovarian cortex. Spatio-temporal computer simulation suggests that interfollicular signals may hinder follicle loss and may therefore drive clustered follicle distribution. In clinical practice, the woman's age should be taken into account when assessing follicle density, as follicle distribution is increasingly clustered with advancing age.

• Tanbo, Tom Gunnar; Mellembakken, Jan Roar; Bjercke, Sverre; Ring, Eva Kristina; Åbyholm, Thomas & Fedorcsák, Péter (2018). Ovulation induction in polycystic ovary syndrome. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 97(10), p. 1162–1167. doi: 10.1111/aogs.13395. Full text in Research Archive Show summary

  The objective of this narrative review was to suggest a rational order of treatment choices in anovulatory women with polycystic ovary syndrome (PCOS), for whom a multitude of treatment options exist. In obese/overweight women with PCOS the importance of weight reduction should be stressed. Inositol, a dietary supplement with a documented effect on ovulation and without adverse effects in the doses recommended, may be suggested. Additional first‐line medical alternatives include insulin sensitizers, selective estrogen receptor modulators, and aromatase inhibitors. Of these, the aromatase inhibitor letrozole and the combination of clomiphene citrate and metformin have the highest rates of ovulation and live birth. Second‐line treatments are ovarian electrocautery and low‐dose follicle‐stimulating hormone stimulation. Controlled ovarian stimulation with in vitro fertilization, should be considered the last option as it carries a significant risk of ovarian hyperstimulation syndrome in patients with PCOS.

• Tanbo, Tom Gunnar & Fedorcsák, Péter (2017). Endometriosis-associated infertility: aspects of pathophysiological mechanisms and treatment options. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 96(6), p. 659–667. doi: 10.1111/aogs.13082. Full text in Research Archive Show summary

  Endometriosis is a common condition in women of reproductive age. In addition to pain, endometriosis may also reduce fertility. The causes of infertility in women with endometriosis may range from anatomical distortions due to adhesions and fibrosis to endocrine abnormalities and immunological disturbances. In some cases, the various pathophysiological disturbances seem to interact through mechanisms so far not fully understood. Whether surgery should be offered as a treatment option in endometriosis‐associated infertility has become controversial, partly due to its modest or undocumented effect. Medical or hormonal treatment alone has little or no effect and should only be used in conjunction with assisted reproductive technology (ART). Of the various methods of ART, intrauterine insemination, due to its simplicity, can be recommended in women with minimal or mild peritoneal endometriosis, even though insemination may yield a lower success rate than in women without endometriosis. In vitro fertilization (IVF) is an effective treatment option in less‐advanced disease stages, and the success rates are similar to the results in other causes of infertility. However, women with more advanced stages of endometriosis have lower success rates with IVF. This is the peer reviewed version of the article, which has been published in final form at https://doi.org/10.1111/aogs.13082. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

• Pelanis, Rasa; Mellembakken, Jan Roar; Sundström-Poromaa, Inger; Berg, Pernille Ravn; Morin-Papunen, Laure & Tapanainen, Juha S. [Show all 12 contributors for this article] (2017). The prevalence of type 2 diabetes is not increased in normal-weight women with PCOS. Human Reproduction. ISSN 0268-1161. 32(11), p. 2279–2286. doi: 10.1093/humrep/dex294. Full text in Research Archive
• Landfors, Miriam; Johansen, Jostein; Aronsen, Jan Magnus; Vågbø, Cathrine Broberg; Doré, Louis C. & He, Chuan [Show all 13 contributors for this article] (2017). Genome-wide profiling of DNA 5-hydroxymethylcytosine during rat Sertoli cell maturation. Cell Discovery. ISSN 2056-5968. 3. doi: 10.1038/celldisc.2017.13. Full text in Research Archive Show summary

  Sertoli cells have dual roles during the cells’ lifetime. In the juvenile mammal, Sertoli cells proliferate and create the structure of the testis, and during puberty they cease to proliferate and take on the adult role of supporting germ cells through spermatogenesis. Accordingly, many genes expressed in Sertoli cells during testis formation are repressed during spermatogenesis. 5-Hydroxymethylcytosine (5hmC) is a DNA modification enzymatically generated from 5mC and present in all investigated mammalian tissues at varying levels. Using mass spectrometry and immunofluorescence staining we identified a substantial Sertoli cell-specific global 5hmC increase during rat puberty. Chemical labeling, pull-down and sequencing of 5hmC-containing genomic DNA from juvenile and adult rat Sertoli cells revealed that genes that lose or gain 5hmC belong to different functional pathways and mirror the functions of the cells in the two different states. Loss of 5hmC is associated with genes involved in development and cell structure, whereas gain of 5hmC is associated with genes involved in cellular pathways pertaining to the function of the adult Sertoli cells. This redistribution during maturation shows that 5hmC is a dynamic nucleotide modification, correlated to gene expression.

• Jørgensen, Hilde; Hill, Abby S.; Beste, Michael T.; Kumar, Manu P.; Chiswick, Evan & Fedorcsák, Péter [Show all 10 contributors for this article] (2017). Peritoneal fluid cytokines related to endometriosis in patients evaluated for infertility. Fertility and Sterility. ISSN 0015-0282. 107(5), p. 1191–1199.e2. doi: 10.1016/j.fertnstert.2017.03.013. Full text in Research Archive
• Landfors, Miriam; Nakken, Sigve; Fusser, Markus; Dahl, John Arne; Klungland, Arne & Fedorcsák, Péter (2016). Sequencing of FTO and ALKBH5 in men undergoing infertility work-up identifies an infertility-associated variant and two missense mutations. Fertility and Sterility. ISSN 0015-0282. 105(5), p. 1170–1179e5. doi: 10.1016/j.fertnstert.2016.01.002. Full text in Research Archive
• Dahl, John Arne; Jung, Inkyung; Aanes, Håvard; Greggains, Gareth; Manaf, Adeel & Lerdrup, Mads [Show all 20 contributors for this article] (2016). Broad histone H3K4me3 domains in mouse oocytes modulate maternal-to-zygotic transition. Nature. ISSN 0028-0836. 537(7621), p. 548–552. doi: 10.1038/nature19360. Full text in Research Archive
• Klungland, Arne; Dahl, John Arne; Greggains, Gareth; Fedorcsák, Péter & Filipczyk, Adam (2016). Reversible RNA modifications in meiosis and pluripotency. Nature Methods. ISSN 1548-7091. 14(1), p. 18–22. doi: 10.1038/nmeth.4111. Full text in Research Archive
• Stensen, Mette Haug; Tanbo, Tom Gunnar; Storeng, Eleftheria (Ritsa) T.; Åbyholm, Thomas & Fedorcsak, Peter (2015). Fragmentation of human cleavage-stage embryos is related to the progression through meiotic and mitotic cell cycles. Fertility and Sterility. ISSN 0015-0282. 103(2), p. 374–381.e4. doi: 10.1016/j.fertnstert.2014.10.031. Full text in Research Archive
• Tanbo, Tom Gunnar; Greggains, Gareth; Storeng, Eleftheria (Ritsa) T.; Busund, Bjørn; Langebrekke, Anton & Fedorcsák, Péter (2015). Autotransplantation of cryopreserved ovarian tissue after treatment for malignant disease - The first Norwegian results. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 94(9), p. 937–941. doi: 10.1111/aogs.12700. Full text in Research Archive
• Stensen, Mette Haug; Tanbo, Tom Gunnar; Storeng, Eleftheria (Ritsa) T. & Fedorcsak, Peter (2014). Advanced glycation end products and their receptor contribute to ovarian ageing. Human Reproduction. ISSN 0268-1161. 29(1), p. 125–134. doi: 10.1093/humrep/det419. Full text in Research Archive
• Wilkosz, Pawel; Greggains, Gareth; Tanbo, Tom Gunnar & Fedorcsak, Peter (2014). Female reproductive decline is determined by remaining ovarian reserve and age. PLOS ONE. 9(10). doi: 10.1371/journal.pone.0108343. 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
• Nilsen, Anja; Fusser, Markus; Greggains, Gareth; Fedorcsak, Peter & Klungland, Arne (2014). ALKBH4 depletion in mice leads to spermatogenic defects. PLOS ONE. 9(8). doi: 10.1371/journal.pone.0105113. Full text in Research Archive
• Polec, Anna; Fedorcsak, Peter; Eskild, Anne & Tanbo, Tom Gunnar (2014). The interplay of human chorionic gonadotropin (hCG) with basic fibroblast growth factor and adipokines on angiogenesis in vitro. Placenta. ISSN 0143-4004. 35(4), p. 249–253. doi: 10.1016/j.placenta.2014.02.002. Full text in Research Archive
• Zheng, Guanqun; Dahl, John Arne; Niu, Yamei; Fedorcsak, Peter; Huang, Chun-Min & Li, Charles J. [Show all 28 contributors for this article] (2013). ALKBH5 Is a Mammalian RNA Demethylase that Impacts RNA Metabolism and Mouse Fertility. Molecular Cell. ISSN 1097-2765. 49(1), p. 18–29. doi: 10.1016/j.molcel.2012.10.015. Full text in Research Archive
• Opøien, Hans Kristian; Fedorcsak, Peter; Polec, Anna; Stensen, Mette Haug; Åbyholm, Thomas & Tanbo, Tom Gunnar (2013). Do endometriomas induce an inflammatory reaction in nearby follicles? Human Reproduction. ISSN 0268-1161. 28(7), p. 1837–1845. doi: 10.1093/humrep/det087. Full text in Research Archive
• Eskild, Anne; Fedorcsak, Peter; Mørkrid, Lars & Tanbo, Tom Gunnar (2012). Maternal body mass index and serum concentrations of human chorionic gonadotropin in very early pregnancy. Fertility and Sterility. ISSN 0015-0282. 98(4), p. 905–910. doi: 10.1016/j.fertnstert.2012.06.011. Full text in Research Archive
• Opøien, Hans Kristian; Fedorcsak, Peter; Omland, Anne Katerine; Åbyholm, Thomas; Bjercke, Sverre & Ertzeid, Gudvor [Show all 9 contributors for this article] (2012). In vitro fertilization is a successful treatment in endometriosis-associated infertility. Fertility and Sterility. ISSN 0015-0282. 97(4), p. 912–918. doi: 10.1016/j.fertnstert.2012.01.112. Full text in Research Archive
• Polec, Anna; Raki, Melinda; Åbyholm, Thomas; Tanbo, Tom Gunnar & Fedorcsak, Peter (2011). Interaction between granulosa-lutein cells and monocytes regulates secretion of angiogenic factors in vitro. Human Reproduction. ISSN 0268-1161. 26(10), p. 2819–2829. doi: 10.1093/humrep/der216. Full text in Research Archive
• Opøien, Hans Kristian; Fedorcsak, Peter; Åbyholm, Thomas & Tanbo, Tom Gunnar (2011). Complete surgical removal of minimal and mild endometriosis improves outcome of subsequent IVF/ICSI treatment. Reproductive Biomedicine Online. ISSN 1472-6483. 23(3), p. 389–395. doi: 10.1016/j.rbmo.2011.06.002. Full text in Research Archive
• Mellembakken, Jan Roar; Berga, Sarah L.; Kilen, Mirjam; Tanbo, Tom Gunnar; Åbyholm, Thomas & Fedorcsak, Peter (2011). Sustained fertility from 22 to 41 years of age in women with polycystic ovarian syndrome. Human Reproduction. ISSN 0268-1161. 26(9), p. 2499–2504. doi: 10.1093/humrep/der214. Full text in Research Archive
• Fedorcsak, Peter; Polec, Anna; Raki, Melinda; Holm, Ruth; Jebsen, Peter Wilhelm & Åbyholm, Thomas (2010). Differential Release of Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases by Human Granulosa-Lutein Cells and Ovarian Leukocytes. Endocrinology. ISSN 0013-7227. 151(3), p. 1290–1298. doi: 10.1210/en.2009-0605. Full text in Research Archive
• Stensen, Mette Haug; Tanbo, Tom Gunnar; Storeng, Eleftheria (Ritsa) T.; Åbyholm, Thomas & Fedorcsak, Peter (2010). Routine morphological scoring systems in assisted reproduction treatment fail to reflect age-related impairment of oocyte and embryo quality. Reproductive Biomedicine Online. ISSN 1472-6483. 21(1), p. 118–125. doi: 10.1016/j.rbmo.2010.03.018. Full text in Research Archive
• Bjercke, Sverre; Tanbo, Tom Gunnar; Åbyholm, Thomas; Omland, Anne Katerine; Opøien, Hans Kristian & Fedorcsak, Peter (2010). Clinical outcome following stimulation with highly purified hMG or recombinant FSH in patients undergoing their first treatment cycle of IVF or ICSI. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 89(8), p. 1053–1060. doi: 10.3109/00016349.2010.499450. Full text in Research Archive
• Polec, Anna; Tanbo, Tom Gunnar & Fedorcsak, Peter (2009). Cellular Interaction Regulates Interleukin-8 Secretion by Granulosa-Lutein Cells and Monocytes/Macrophages. American Journal of Reproductive Immunology. ISSN 8755-8920. 61(1), p. 85–94. doi: 10.1111/j.1600-0897.2008.00668.x. Full text in Research Archive
• Ertzeid, Gudvor; Fedorcsak, Peter; Åbyholm, Thomas & Tanbo, Tom Gunnar (2006). Elective single embryo transfer in assisted reproduction. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 126(23), p. 3101–3102. Full text in Research Archive
• Omland, Anne Katerine; Bjercke, Sverre; Ertzeid, Gudvor; Fedorcsak, Peter; Oldereid, Nan Birgitte & Storeng, Ritsa [Show all 8 contributors for this article] (2006). Intracytoplasmic sperm injection (ICSI) in unexplained and stage I endometriosis-associated infertility after fertilization failure with in vitro fertilization (IVF). Journal of Assisted Reproduction and Genetics. ISSN 1058-0468. 7(8), p. 351–356. Full text in Research Archive
• Omland, Anne Katerine; Åbyholm, Thomas; Fedorcsak, Peter; Ertzeid, Gudvor; Oldereid, Nan Birgitte & Bjercke, Sverre [Show all 7 contributors for this article] (2005). Pregnancy outcome after IVF and ICSI in unexplained, endometriosis-associated and tubal factor infertility. Human Reproduction. ISSN 0268-1161. 20(3), p. 722–727. Full text in Research Archive Show summary

  This study was undertaken in order to compare pregnancy outcome after IVF and ICSI in unexplained and endometriosis-associated infertility using tubal factor infertility as controls. METHODS: This was a retrospective cohort study of early IVF/ICSI pregnancies verified by serum hCG measurement, comparing the subsequent outcome in unexplained (n = 274) and minimal endometriosis-associated (n = 212) with tubal factor (n = 540) infertility as controls. From January 1990 to December 2002, 1026 conception cycles after treatment with IVF or ICSI complied with the inclusion criteria. RESULTS: Live birth rate, twin birth rate after transfer of two embryos and abortion rate prior to 6 weeks of gestation were superior for the unexplained (78.8, 23.5 and 11.7%) compared to endometriosis-associated (66.0, 15.0 and 19.3%) and tubal factor (66.7, 18.1 and 18.0%) infertility groups (P < 0.05). Compared to the endometriosis-associated, the unexplained infertility group attained a higher pregnancy rate after the first treatment cycle (P < 0.05). CONCLUSIONS: The overall better outcome for the unexplained infertility group with respect to live birth rate, twin birth rate and early abortion rate compared to the minimal peritoneal endometriosis-associated and tubal factor infertility groups might be a guide to select diagnostic groups for single embryo transfer and be useful in patient counselling

• Bjercke, Sverre; Fedorcsak, Peter; Åbyholm, Thomas; Storeng, Ritsa; Ertzeid, Gudvor & Oldereid, Nan Birgitte [Show all 8 contributors for this article] (2005). IVF/ICSI outcome and serum LH concentration on day 1 of ovarian stimulation with recombinant FSH under pituitary suppression. Human Reproduction. ISSN 0268-1161. 20. Full text in Research Archive
• Lund, Hanne S.; Alstad, Heidi; Fedorcsak, Peter; Storeng, Rita & Hemmersbach, Peter J (2005). Endogenous nandrolone production: studies in granulosa cells from patients with polycystic ovary syndrom (PCOS). In Schänzer, Wilhelm; Geyer, Hans; Gotzmann, Andrea & Mareck, Ute (Ed.), Recent Advances in Doping Analysis (13). Sportverlag Strauss. ISSN 9783939390138. p. 483–486. Full text in Research Archive
• Fedorcsak, Peter; Dale, Per Olav; Storeng, Ritsa; Ertzeid, Gudvor; Bjercke, Sverre & Oldereid, Nan [Show all 9 contributors for this article] (2004). Impact of overweight and underweight on assisted reproduction treatment. Human Reproduction. ISSN 0268-1161. 19(11), p. 2523–2528. Full text in Research Archive
• Dale, P.O.; Tanbo, T; Ertzeid, Gudvor; Bjercke, S; Oldereid, N.B. & Fedorcsak, Peter [Show all 7 contributors for this article] (2004). The impact of insulin resistance on the outcome of laparoscopic ovarian electrocautery in infertile women with the polycystic ovary syndrome. Gynecological Endocrinology. ISSN 0951-3590. 19, p. 182–189. Full text in Research Archive
• Fedorcsak, Peter (2003). Effects of leptin and leukemia inhibitory factor on preimplantation development and STAT3 signaling of mouse embryos in vitro. Biology of Reproduction. ISSN 0006-3363. 69, p. 1531–1538. Full text in Research Archive
• Fedorcsak, Peter & Åbyholm, Thomas (2003). The effect of metformin on ovarian stimulation and in vitro fertilization in insulin resistant women with polycystic ovarian syndrome: an open randomized crossover trial. Gynecological Endocrinology. ISSN 0951-3590. 17, p. 207–214. Full text in Research Archive
• Omland, Anne Katerine; Fedorcsak, Peter; Storeng, Ritsa; Dale, Per Olav; Åbyholm, Thomas & Tanbo, Tom [Show all 7 contributors for this article] (2002). Different aetiological mechanisms for unexplained and endometriosis-associated infertility cannot be inferred from unstimulated IVF cycles using HCG to induce ovulation. Human Reproduction. ISSN 0268-1161. 17, p. 1927–1927. Full text in Research Archive
• Omland, Anne Katerine; Fedorcsak, Peter; Storeng, Ritsa; Dale, Per Olav; Åbyholm, Thomas & Tanbo, Tom (2001). Natural cycle IVF in unexplained, endometriosis-associated and tubal factor infertility. Human Reproduction. ISSN 0268-1161. 16(12), p. 2587–2592. Full text in Research Archive
• Fedorcsak, Peter; Dale, Per Olav; Storeng, Ritsa; Tanbo, Tom & Åbyholm, Thomas (2001). The impact of obesity and insulin resistance on the outcome of IVF or ICSI in women with polycystic ovarian syndrome. Human Reproduction. ISSN 0268-1161. 16, p. 1086–1091. Full text in Research Archive
• Wang, Y H.; Fedorcsak, Peter; Dale, Per Olav; Storeng, Ritsa; Åbyholm, Thomas & Tanbo, Tom (2001). Simplification of continous infusion of glucose with model assessment in the evaluation of insulin resistance in PCOS women. Gynecological Endocrinology. ISSN 0951-3590. 15, p. 192–197. Full text in Research Archive
• Fedorcsak, Peter; Storeng, Ritsa; Dale, Per Olav; Tanbo, Tom & Åbyholm, Thomas (2000). Impaired insulin action on granulosa-lutein cells from patients with polycystic ovary syndrome and insulin resistance. Gynecological Endocrinology. ISSN 0951-3590. 14, p. 327–336. Full text in Research Archive
• Fedorcsak, Peter; Storeng, Ritsa; Dale, Per Olav; Tanbo, Tom & Åbyholm, Thomas (2000). Obesity is associated with early pregnancy loss after IVF or ICSI. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 1, p. 43–48. Full text in Research Archive

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• Fedorcsak, Peter Zoltan & Tanbo, Tom Gunnar (2025). Fertilitetsbehandling ved kreft - hvor er vi i dag? Tidsskrift for kreftsykepleiere. 2025(2), p. 42–47. Full text in Research Archive
• Haugnes, Hege Sagstuen; Myklebust, T.Å.; Brydøy, Marianne; Negaard, H.; Seljeflot, Eline Bragedatter & Kleveland, Camilla Rørslett [Show all 9 contributors for this article] (2025). 1053P Post-diagnosis (post-TC) paternity in testicular cancer survivors (TCSs): A controlled cohort study. Annals of Oncology. ISSN 0923-7534. 36, p. 664–664. doi: 10.1016/j.annonc.2025.08.1693. Full text in Research Archive Show summary

  TCSs can father at least one post-TC child though with 10% lower probability compared to Controls. Individiualized estimation of the probability of post-TC paternity requires consideration of age at TC diagnosis, the number of pre-TC children, type and intensity of treatment

• Fedorcsak, Peter Zoltan (2025). Barneønske hos brystkreftpasienter. Hvilke muligheter finnes? Full text in Research Archive
• Fedorcsak, Peter Zoltan (2025). Female fertility preservation in Norway. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2025). Hvor mange egg trengs for ett barn? Behandling og forskning på RMA. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2025). Clinical samples from the Department of Reproductive Medicine. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2025). Preimplantasjonsgenetisk test for aneuploidi. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2025). Fertilitetsbehandling ved kreft – status. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2025). Barneønske og fertilitet ved diffuse gliomer. Full text in Research Archive
• Massiah, Nadine Simone; Tanbo, Tom Gunnar; Rajkumar, Hemamaalini; Vera-Rodriguez, Maria & Fedorcsak, Peter Zoltan (2025). OncoFertBot: quality and safety of a conversational AI assistant for retrieving oncofertility guidelines for clinical decision-making. Human Reproduction. ISSN 0268-1161. 40(Supplement 1). doi: https:/scholar.google.no/scholar?oi=bibs&cluster=861185255337094396&btnI=1&hl=no. Full text in Research Archive
• Fedorcsak, Peter Zoltan; Massiah, Nadine Simone & Tanbo, Tom Gunnar (2025). Educational games during seminars improve medical students’ knowledge of reproductive endocrinology and infertility. Human Reproduction. ISSN 0268-1161. 40(Supplement 1). doi: https:/academic.oup.com/humrep/article/40/Supplement_1/deaf097.946/8171041?login=false. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2024). Ferdighetstrening med SimSamBot. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2024). Fruktbarhetsbevarende behandling. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2024). Øv på strukturert pasientsamtale med SimSamBot. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2024). Tre forslag til aktiv undervisning. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2024). Fertilitetsbevarende behandling. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2024). Research area 4: developmental failure of oocytes and embryos. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2023). Hvilke muligheter gir bioteknologiloven? Full text in Research Archive
• Fedorcsak, Peter Zoltan (2023). BRCA og fertilitet. Full text in Research Archive
• Fedorcsak, Peter Zoltan (2023). Using more cooperative learning in undergraduate medical education. Full text in Research Archive
• Fedorcsak, Peter Zoltan & Arntzen, Vebjørn (2023). Shared software development through openEHR archetypes and templates. Full text in Research Archive
• Tiller, Heidi; Fedorcsák, Péter & Skogen, Bjørn Ragnar (2016). Old tools revisited give hope - new treatment option for families with a history of severe FNAIT complications. Acta Obstetricia et Gynecologica Scandinavica. ISSN 0001-6349. 95(4), p. 486–487. doi: 10.1111/aogs.12842. 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
• Mellembakken, Jan Roar; Berga, Sarah L.; Kilen, Mirjam; Tanbo, Tom Gunnar; Abyholm, Thomas & Fedorcsak, Peter (2011). Unchanged Fertility with Age in Women with Polycystic Ovarian Syndrome. Reproductive Sciences. ISSN 1933-7191. 18(3), p. 253A–253A. Full text in Research Archive
• Polec, Anna; Raki, Melinda; Tanbo, Tom Gunnar; Åbyholm, Thomas & Fedorcsak, Peter (2011). Interaction between Granulosa-Lutein Cells and Monocytes Regulates Secretion of Angiogenic Factors In Vitro. Reproductive Sciences. ISSN 1933-7191. 18(3), p. 279A–279A. Full text in Research Archive
• Stensen, Mette Haug; Tanbo, Tom Gunnar; Storeng, R.; Abyholm, T. & Fedorcsak, Peter (2011). Human ovarian ageing: a role of advanced glycation endproducts (AGE) and the receptor RAGE? Human Reproduction. ISSN 0268-1161. 26, p. I235–I236. Full text in Research Archive
• Polec, Anna; Raki, Melinda; Tanbo, Tom Gunnar; Abyholm, Thomas & Fedorcsak, Peter (2010). Interaction between granulosa-lutein cells and monocytes regulates secretion of angiogenic factors in vitro. Human Reproduction. ISSN 0268-1161. 25, p. I287–I288. Full text in Research Archive
• Opøien, Hans Kristian; Fedorcsak, Peter; Åbyholm, Thomas; Tanbo, Tom Gunnar & Tanbo, Tom (2010). Complete surgical removal of minimal and mild endometriosis improves outcome of subsequent assisted reproduction treatment. Human Reproduction. ISSN 0268-1161. 25(Supp. 1), p. I10–I10. Full text in Research Archive
• Alstad, Heidi; Lund, Hanne S.; Fedorcsak, Peter; Storeng, Rita & Hemmersbach, Peter J (2005). Endogenous nandrolone production: Studies in granulosa cells from patients with polycystic ovary syndrome (PCOS). Full text in Research Archive
• Fedorcsak, Peter (2003). Phosphorylation of STAT 3 protein in trophectoderm and inner cell mass cells of mouse blastocysts in vitro. Full text in Research Archive
• Jåthun, Solveig; Lund, H.; Fedorcsak, Peter; Storeng, Ritsa; Torjesen, Peter A. & Hemmersbach, Peter J (2002). Synthesis of Nandrolone in the human ovary. Full text in Research Archive
• Storeng, Ritsa; Fedorcsak, Peter; Bjerknes, G.; Frøland, E.; Haug, M. & Grøthe, A. G. [Show all 10 contributors for this article] (2002). Comparison of ICSI outcome in male and non-male factor infertility. Full text in Research Archive
• Fedorcsak, Peter & Storeng, Ritsa (2002). Leukemia inhibitory factor (LIF) neutralizes the inhibitory effect of leptin on the preimplantation development of mouse embryos in vitro. Full text in Research Archive
• Fedorcsak, Peter & Storeng, Ritsa (2002). Fat hormone leptin impairs embryo development in mice. Full text in Research Archive
• Jåthun, Solveig; Fedorcsak, Peter; Storeng, Ritsa; Lund, H.; Hemmersbach, Peter J & Torjesen, Peter A. (2002). Nandrolone (19-nortestosterone) is a by-product of the estrogen aromatase of the human ovary. Full text in Research Archive
• Fedorcsak, Peter; Storeng, Ritsa; Dale, Per Olav; Tanbo, Tom; Torjesen, Peter A. & Åbyholm, Thomas (2000). Leptin and leptin binding activity in the preovulatory follicle of polycystic ovary syndrome. Full text in Research Archive

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