Roungsin ChoavaratanaIsarin ThanaboonyawatPitak LaokirkkiatJaparath PrechapanichSingpetch SuksompongOrawan MekemaharnSomsin PetyimMahidol University2018-11-232018-11-232015-01-01Gynecologic and Obstetric Investigation. Vol.79, No.3 (2015), 153-1591423002X037873462-s2.0-84926418584https://repository.li.mahidol.ac.th/handle/20.500.14594/36727© 2014 S. Karger AG, Basel. Background/Aims: Follicle-stimulating hormone (FSH) priming has been studied in in vitro matured oocytes for oocyte maturation rate, embryo quality, and pregnancy rate with discouraging results. This study aimed to initiate FSH stimulation later, i.e. on day 6, to prolong natural endometrial priming and promote oocyte maturation. Methods: Forty polycystic ovarian syndrome (PCOS) patients were enrolled into a single, blinded (investigator), randomized, controlled study, and randomly allocated to group 1 (no FSH priming) or group 2 (day 6 recombinant FSH priming). Oocytes were retrieved after human chorionic gonadotropin injection on day 10. After 27 or 51 h of incubation, only mature oocytes were denuded and fertilized by intracytoplasmic sperm injection. Two day 3 embryos were transferred in most patients. Rates of oocyte maturation, cleavage, and pregnancy were compared. Results: The oocyte maturation rates within 51 h were 62.6 and 72.7% in groups 1 and 2, respectively (p < 0.01). The embryo cleavage rate was significantly higher in group 2 than in group 1 (77.3 vs. 63.6%, p < 0.05). The pregnancy rate was higher in group 1 than in group 2 (50 vs. 30%, p > 0.05). Conclusion: FSH priming is beneficial for promotion of the maturation and quality of oocytes, leading to a higher embryo cleavage rate and lower rate of pregnancy loss.Mahidol UniversityMedicineArticleSCOPUS10.1159/000367660