Comparable Pregnancy Loss and Neonatal Birthweights in Frozen Embryo Transfer Cycles Using Vitrified Embryos from Progestin-Primed Ovarian Stimulation and GnRH Analogue Protocols: A Retrospective Cohort Study.

Background: The potential correlation between progestin-primed ovarian stimulation (PPOS) and the risk of compromised embryo competence still lacks sound evidence. Methods: A large retrospective cohort study was used to compare the incidence of pregnancy loss and neonatal birthweights in frozen embryo transfer (FET) cycles using embryos from PPOS and GnRH analogue protocols. Propensity matched scores were used to balance the baseline confounders. Results: A total of 5744 matched cycles with positive hCG test were included to compare the pregnancy outcomes. The incidence of pregnancy loss was similar between PPOS and GnRH analogue groups (19.2% vs. 18.4%, RR 1.02 (0.97, 1.06), p > 0.05). The neonatal birthweights were comparable between two groups, respectively, for singleton births (3337.0 ± 494.4 g vs. 3346.0 ± 515.5 g) and in twin births (2496.8 ± 429.2 g vs. 2533.2 ± 424.2 g) (p > 0.05). Conclusions: The similar incidence of pregnancy loss and neonatal birthweights in FET cycles using embryos from PPOS provided us with a more complete picture about the safety of PPOS.