Abstract
Background: It is paramount to consider the appropriate preparation of the endometrium to receive the transferred embryos as the amount of frozen embryo transfer (FET) cycles is increasing worldwide. However, there remains lack of evidence about what is the most optimal protocol of endometrial preparation regarding pregnancy outcomes in different subgroup of infertile women. This retrospective cohort study was aim to explore the best endometrial preparation protocols among different maternal age groups.Methods: A total of 16870 FET cycles were categorized into three groups based on endometrial preparation protocols: Natural cycle (NC n=3893), artificial cycles (AC, n=11459) and AC with pretreatment with GnRH-a (AC+GnRH-a, n=1518). Logistic regression was performed to investigate the independent effect of endometrial preparation protocols on IVF pregnancy outcomes. Subgroup analyses were conducted to evaluate the most optimal endometrial preparation protocols for different maternal age groups.Results: In overall populations, after controlling for potential confounders, the incidence of live birth (NC as reference; AC: adjusted odds ratio (aOR) =0.840, 95%CI 0.774-0.912; AC+GnRHa: aOR=0.907, 95%CI 0.795-1.034) in NC was significantly higher than that of AC, while comparable to that of AC+GnRH-a. The early miscarriage rate (AC: aOR=1.413, 95%CI 1.220-1.638; AC+GnRHa: aOR=1.537, 95%CI 1.232-1.919) was significantly lower in NC compared to either AC group. In younger women, the live birth rates (AC: aOR=0.894, 95%CI 0.799-1.001; AC+GnRHa: aOR=1.111, 95%CI 0.923-1.337) were comparable between the three groups, with a slightly higher in AC+GnRH-a. Early miscarriage rate was only significantly lower in NC compared to that of AC without GnRH-a (aOR=1.452, 95%CI 1.159-1.820). While in older women, the incidence of live birth (AC: aOR=0.811, 95%CI 0.718-0.916; AC+GnRHa: aOR=0.760, 95%CI 0.626-0.923) was significantly higher, and early miscarriage (AC: aOR=1.358, 95%CI 1.114-1.655; AC+GnRHa: aOR=1.717, 95%CI 1.279-2.305) was significantly lower in NC compared to those of two AC groups.Conclusions: NC protocol is associated with lower early miscarriage late in overall IVF population. There is a mild favor of AC+GnRH-a in younger women, while the priority of NC is remarkable in older women. Maternal age should be a considerable factor when determine endometrial preparation method for FET.
Optimal Endometrial Preparation Protocols for Frozen-thawed Embryo Transfer Cycles by Maternal Age
