Effects of Different Endometrial Preparation Protocols on Pregnancy Outcomes in Women with Polycystic Ovarian Syndrome Undergoing Frozen Embryo Transfer: A Network Meta-Analysis

Aim: 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). Method: 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. Results: Seventeen studies met the inclusion criteria, encompassing 16,082 FET cycles (four randomized 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 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 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 minimizing the MR. Conclusion: 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.