Effect of different endometrial preparation protocols on pregnancy outcome of selective blastocyst transplantation

Abstract Objective To investigate the effect of endometrial preparation methods prior to elective single blastocysttransfer on pregnancy outcome. Methods A retrospective case-control study was conducted to analyze the clinical data of 595 patients who received frozen-thawed embryo transfertreatment from January 2019 to November 2022 in the fertility center of Huzhou Maternity & Child Health Care Hospital, divided into GnRH-a+HRT group(n=213), HRT group(n=149), mNC group(n=233). Results The biochemical pregnancy rate and early abortion rate of mNC group were lower than GnRH-a+HRT group and HRT group (P＞0.05). The clinical pregnancy rate of mNC group was higher than GnRH-a+HRT group and HRT group (P＞0.05). The live birth rate in mNC group was significantly higher than that in GnRH-a+HRT group and HRT group (44.2% vs.34.3% vs. 36.2%, P＜0.05). The clinical pregnancy rate of mNC group was higher than GnRH-a+HRT group and HRT group (P＞0.05). The live birth rate in mNC group was significantly higher than that in GnRH-a+HRT group and HRT group (50.0% vs.34.6% vs.38.9%, P＜0.05). The early abortion rate in mNC group was significantly lower than that in GnRH-a+HRT group and HRT group (11.0% vs.26.6% vs.12.2%, P＜0.05). Conclusion In freeze-thaw eSBT cycles, especially in high-quality blastocyst transfer cycles, mNC has better pregnancy outcomes than GnRH-a+HRT and HRT. In clinical work, the mNC protocol was suggested to be used to elective single blastocyst transfer cycles.