A randomized controlled trial to compare the live birth rate of the first frozen embryo transfer following the progestin-primed ovarian stimulation protocol vs. the antagonist protocol in women with an anticipated high ovarian response

Objective: To compare the live birth rate of the first frozen embryo transfer (FET) after ovarian stimulation by the progestin-primed ovarian stimulation (PPOS) protocol vs. the antagonist protocol in women with an anticipated high ovarian response who were undergoing in vitro fertilization. Design: Randomized controlled trial. Setting: A tertiary assisted reproduction center. Patients: Women with infertility aged <43 years undergoing the first in vitro fertilization cycle and having antral follicle count of >15. Interventions: Medroxyprogesterone 10 mg daily was given from the start of ovarian stimulation until the day of ovulation trigger in the PPOS protocol. In the antagonist protocol, an antagonist 0.25 mg daily was given from the sixth day of ovarian stimulation until the day of ovulation trigger. Blinding was not possible for women or physicians but the biostatistician was blinded to the group assignment. Main Outcome Measure: Live birth rate of the first FET cycle. Results: A total of 784 women were recruited from June 2020 and October 2021 and assigned randomly in a 1:1 ratio into two groups: PPOS group (n = 392) and antagonist group (n = 392). Embryo transfer was either cancelled or postponed in 62 women (62/392, 15.8%) in the PPOS group and 65 (65/392, 16.6%) in the antagonist group because of no transferable embryos or no FET within 6 months after randomization. The two groups were similar in demographic characteristics and the numbers of oocytes obtained or fertilized, cleaving embryos, good-quality embryos at day 3, blastocysts developed, and embryos or blastocysts frozen. There was no statistically significant difference in the live birth rate of the first FET cycle between the PPOS and antagonist groups on the basis of both the intention-to-treat analysis (37.5.0% [147/392] vs. 32.7% [128/392]; relative risk, 1.148 [95% confidence interval, 0.949-1.390]) and per-protocol analysis (44.5% [147/330] vs. 39.1% [128/327]; relative risk, 1.138 [95% confidence interval, 0.950-1.364]). Both groups showed comparable clinical pregnancy, ongoing pregnancy, miscarriage, multiple pregnancy, ectopic pregnancy, and cumulative live birth rates. Conclusion: The live birth rates of the first FET following the PPOS and antagonist protocols were comparable in women with an anticipated high ovarian response.