P–700 Increased progesterone to mature oocyte index is associated with lower top-quality embryo rate in GnRH antagonist protocols

Study question Do progesterone elevation (PE) on trigger day and progesterone to mature oocyte index (PMOI) affect embryo quality and the chance of live birth? Summary answer The top-quality embryo rate is decreased by increasing PMOI, but it has no association with absolute serum progesterone levels. What is known already Progesterone elevation have been reported to significantly decrease pregnancy and implantation rates. The main mechanism of this adverse effect is mainly related to an asynchrony between the endometrium and the embryo. Many of the previous studies have failed to show a significant impact of PE on embryo quality and the success of subsequent frozen-thawed embryo transfer (FET) cycle. However, PMOI was suggested to be more predictive than PE of ART outcome and might be associated with embryo quality. Study design, size, duration A single-centre retrospective cohort study was conducted. All FET cycles performed in a university hospital infertility centre between January 2016 and December 2019 were reviewed. A total of 44 patients who had PE (>1.5 ng/ml) on trigger day and 134 patients who did not have PE were assessed. Participants/materials, setting, methods The study group consisted of patients who had PE (>1.5 ng/mL) during fresh COS cycle and the control group consisted of patients who did not have PE. In addition to effect of PE on subsequent FET cycle outcome, an association between PMOI and embryo quality was assessed. The threshold level to define increased PMOI (>0.12 ng/ml) was calculated as the median level of the whole study cohort. Main results and the role of chance The mean ages of the study and control groups were 30.4±5.4 years and 31.1±5.6 years, respectively (P = 0.413). Although the number of oocytes collected and MII oocytes were significantly higher in patients with PE, the total number of frozen embryos were similar between the groups. There were no significant differences concerning the outcome measures including live birth rate in the subsequent FET cycle between participants with and without PE (27.3% vs. 23.9%, respectively; P = 0.652). The rate of top-quality embryos was similar between participants with and without PE (43% vs. 52%, respectively; P = 0.370). However, the rate of top-quality embryos was significantly lower in cycles with PMOI>0.12 ng/ml than in cycles PMOI<0.12 ng/ml (42% vs. 56%, respectively; P = 0.027). Limitations, reasons for caution The retrospective design and the small sample size derived from a single institution. Wider implications of the findings: Increased PMOI, which is associated to lower top-quality embryo rate, may in turn result in diminished cumulative live birth rate. Trial registration number Not applicable