Retrospective Review of Reproductive Outcomes Comparing Vaginal Progesterone to Intramuscular Progesterone as Luteal Support in Frozen Embryo Transfer Cycles.

OBJECTIVE: Recent literature suggests that progesterone in oil (PIO) is superior to vaginal progesterone (VP; Prometrium) for endometrial preparation in frozen embryo transfer cycles (FET), improving the live birth rate and reducing the rate of miscarriage. PIO has disadvantages including cost, pain, and stress of administration. The objective of this study was to evaluate whether VP is non-inferior to PIO for medicated FET cycles.

METHODS: We conducted a retrospective analysis comparing pregnancy, miscarriage, and live birth rates for PIO versus VP for medicated FET cycles, from 2017 to 2020 at a single fertility clinic. A total of 745 participants were included in the study; 438 received VP, and 307 received PIO. Univariate and multivariate binary and ordinal logistic regression analyses were performed to compare the rates of pregnancy, miscarriage, and live birth between VP and PIO.

RESULTS: Our data demonstrated no difference between PIO and VP with respect to the rates of pregnancy (51% vs. 53%), miscarriage (20% vs. 18%), or live birth (31% vs. 34%) (all P > 0.05). For participants taking PIO, the odds of pregnancy were 0.93 [95% CI (0.70, 1.25), P = 0.65] that of participants on VP.

CONCLUSION: In our single-centre experience, VP was non-inferior to PIO for endometrial preparation in FET cycles.