Efficacy of Natural Cycle versus GnRH-a Down Regulation Cycle of Endometrial Preparation in Minimal and Mild endometriosis Patients Undergoing Frozen-Thawed Embryo Transfer

Abstract

Background Minimal and mild endometriosis patients with infertility are treated by in vitro fertilization and embryo transfer/intracytoplasmic sperm injection (IVF-ET/ICSI) in recent years. However, inconsistencies in findings within and across individual studies raise concerns as to determine which method is the best treatment, especially in the frozen-thawed embryo transfer cycle (FET). We hope to compare the efficacy of natural cycle versus GnRH-a down regulation cycle endometrial preparations in minimal and mild endometriosis patients undergoing FET. Methods We retrospectively analyzed a cohort of 1170 minimal and mild endometriosis patients receiving FET at the Reproductive Medicine Centre from Chengdu Jinjiang Hospital for Maternal and Child Health Care from January 1, 2016 to December 31, 2018. They were assigned to the natural cycle group and the GnRH-a down regulation cycle group based on endometrial preparation protocols. Baseline characteristics, frozen-thawed embryo transfer cycle and pregnancy outcomes were compared between the two groups. Results There were nonsignificant differences in baseline characteristics including age, BMI, types of infertility, the duration of infertility and the delivery history between the natural cycle group and the GnRH-a down regulation cycle group (P>0.05). The biochemical pregnancy rate (63.62% v.s. 53.83%), clinical pregnancy rate (56.10% v.s. 47.49%), implantation rate (43.19% v.s. 34.88%) and live birth rate (44.31% v.s. 35.84%) in the natural cycle group were significantly higher than those in the GnRH-a down regulation cycle group (P<0.05). However, there were nonsignificant differences in the multiple birth rate, abortion rate, ectopic pregnancy rate, premature birth rate, neonatal weight and length between the two groups (P>0.05). The multivariate regression analysis showed that age, anti-Müllerian hormone (AMH), the number of transplanted high-quality blastocysts and endometrial preparation protocols were associated with the live birth rate in minimal and mild endometriosis women undergoing FET (P<0.05). Conclusion Compared with GnRH-a down regulation cycle, natural cycle endometrial preparation of FET is a prominent endometrial preparation method for improving the implantation rate, clinical pregnancy rate, and live birth rate in minimal and mild endometriosis patients, which is more cost-effective in clinical practice.