Letrozole protocol associated with higher live birth and lower adverse outcomes versus estrogen-progesterone in ovulation disorder FET

Several endometrial preparation protocols are available in frozen-thawed embryo (FET) transfer cycles. The aim of this study was to compare the clinical outcomes, obstetrical and neonatal complications between ovulation disorder patients undergoing FET with ovulation induction protocol and patients with artificial programmed protocol. A single-center retrospective cohort study using propensity-score matching (PSM) was conducted. Ovulation disorder women undergoing FET using ovulation induction medicine Letrozole (OI group), or estrogen/progesterone (EP) for endometrial preparation were included. Clinical outcomes, obstetrical and neonatal complications were compared before and after PSM. Multiple logistic regression models were performed to demonstrate the independent impact of endometrial protocols on pregnancy outcomes. A total of 552 women in OI group and 3344 women in EP group were included. As for pregnancy outcomes after PSM, patients in OI group were with significantly higher live birth rate (38.1% vs. 33.4%; P = 0.042), and lower early spontaneous miscarriage rate (13.1% vs. 18.9%; P = 0.032). In singleton birth, the prevalence of GDM (7.9% vs. 14.6%; P = 0.037), and LBW (7.9% vs. 14.1%; P = 0.042) was significantly lower in patients from OI group as compared with EP group. In patients after PSM, after adjusting for covariates, EP protocol was a risk factor of early spontaneous miscarriage rate (OR = 1.450, 95%CI: 1.085-1.963; P = 0.029), GDM (OR = 1.627, 95%CI: 1.288-2.601; P = 0.034), and LBW (OR = 1.852, 95%CI: 1.127-2.250; P = 0.041). As compared with EP protocol, using Letrozole to achieve endometrial preparation prior to FET may yield a decreased risk of early spontaneous miscarriage rate, GDM, and as well as LBW in ovulation disorder patients undergoing FET.