Basal serum progesterone and history of elevated progesterone on the day of hCG administration are significant predictors of late follicular progesterone elevation in GnRH antagonist IVF cycles.

STUDY QUESTION Are there any baseline predictors of progesterone elevation (PE) on the day of human chorionic gonadotrophin (hCG) which are not associated with the intensity of ovarian stimulation in women undergoing in vitro fertilization (IVF) using follicle stimulating hormone (FSH) and gonadotrophin-releasing hormone (GnRH) antagonists? SUMMARY ANSWER Basal (Day 2 of the menstrual cycle) serum progesterone concentration and history of PE are baseline variables that can predict the occurrence of PE on the day of hCG independently of the intensity of ovarian stimulation. WHAT IS KNOWN ALREADY PE on the day of hCG is associated with the magnitude of the ovarian response to stimulation. For this reason, it has been hypothesized that milder ovarian stimulation might reduce the probability of PE. However, given the fact that the number of oocytes retrieved is associated with the probability of live birth, such a strategy should be considered only in patients that are at high risk of PE on the day of hCG. STUDY DESIGN, SIZE, DURATION This is a retrospective analysis of a cohort of fresh IVF/ICSI cycles (n = 1702) performed in a single IVF centre during the period 2001-2015. PARTICIPANTS/MATERIALS, SETTING, METHODS Patients in whom ovarian stimulation was performed with FSH and GnRH antagonists and with basal FSH <14.0 mIU/ml, progesterone (P) ≤1.6 ng/ml and estradiol (E2) ≤80 pg/ml on the same day (prior to the initiation of stimulation) were considered eligible. PE was defined as serum progesterone concentration >1.5 ng/ml. Pre-stimulation characteristics of patients and basal hormonal profile were assessed for their ability to predict the occurrence of PE after ovarian stimulation through generalized estimating equation univariable and multivariable regression analyses, controlling for the effect of ovarian stimulation. Furthermore, a secondary analysis in a subset of patients with multiple IVF cycles explored whether the occurrence of PE in one of the previous cycles included in this study is associated with a significantly higher occurrence of PE elevation in subsequent cycles. MAIN RESULTS AND THE ROLE OF CHANCE Univariable regression analyses showed that female age (OR: 0.97; 95% CI: 0.94-0.99), basal FSH (OR: 0.85; 95% CI: 0.79-0.92) and basal P (OR: 4.20; 95% CI: 2.47-7.12) were baseline variables that could significantly predict PE on the day of hCG. When these variables were entered in the same model as covariates, only basal FSH (OR: 0.86; 95% CI: 0.80-0.94) and basal P (OR: 3.83; 95% CI: 2.24-6.56) could still predict the occurrence of PE. Basal P (OR: 6.30; 95% CI: 3.35-11.82) was the only variable that could significantly predict the occurrence of PE on the day of hCG after adjusting for the intensity of ovarian stimulation. The secondary analysis revealed that history of PE on the day of hCG in a previous cycle was also strongly associated with an increased risk of PE in a subsequent cycle. LIMITATIONS, REASONS FOR CAUTION This is a retrospective analysis and although the effect of the most important confounders was controlled for in the multivariable analysis, the presence of residual bias cannot be excluded. WIDER IMPLICATIONS OF THE FINDINGS The findings of this study might help clinicians identify patients at high risk for late follicular PE and alter the management of their cycle. STUDY FUNDING/COMPETING INTERESTS None. TRIAL REGISTRATION NUMBER Not applicable.