Effects of different endometrial preparation protocols on pregnancy outcomes in women with polycystic ovarian syndrome undergoing frozen embryo transfer: A network meta-analysis

This study aimed to investigate the impact of various endometrial preparation protocols on pregnancy outcomes in women with polycystic ovarian syndrome (PCOS) undergoing frozen embryo transfer (FET). We conducted a comprehensive search of electronic databases, including PubMed, EMBASE, and the Cochrane Library, from their inception until February 2024 to identify relevant studies. The network meta-analysis (NMA) was performed using STATA 14.0 software. Seventeen studies met the inclusion criteria, encompassing 16,082 FET cycles (four randomised controlled trials and thirteen observational studies). Women with PCOS undergoing FET using the gonadotropin-releasing hormone agonist (GnRH-a) + hormone replacement therapy (HRT) protocol demonstrated a higher clinical pregnancy rate (CPR) compared to those using HRT alone (OR 1.50, 95% CI 1.13-1.99). No significant differences were observed in the ongoing pregnancy rate (OPR) and ectopic pregnancy rate (EPR) among the four examined endometrial preparation protocols (human menopausal gonadotropin [HMG]/follicle-stimulating hormone [FSH], letrozole [LE], HRT, and GnRH-a + HRT). Regarding the miscarriage rate (MR), the LE ovulation induction protocol exhibited a lower MR than the HRT protocol (OR 0.59, 95% CI 0.46-0.74). The surface under the cumulative ranking curve (SUCRA) indicated that the GnRH-a + HRT protocol was the most effective for the CPR. In contrast, the LE ovulation induction protocol was the most effective for minimising the MR. Our NMA suggests that the GnRH-a + HRT protocol results in a higher CPR compared to the HRT protocol in PCOS women undergoing FET, albeit with a higher risk of miscarriage. While offering comparable CPRs and OPRs to the GnRH-a + HRT protocol, the LE ovulation induction protocol presents a lower MR than the other endometrial preparation protocols.