Comparison of clinical and neonatal outcomes between day 4 and day 5 embryo transfer cycles stratified by fertilization method

Abstract

Background:In IVF-ET cycles, the day of embryo transfer and the fertilization method are related to the success of the pregnancy.Recent evidence indicates that in IVF-ET, the clinical outcomes of embryo transfer on day 4 (D4 ET) were comparable to those of embryo transfer on day 5 (D5 ET). Few research have compared the clinical and neonatal outcomes of transplants performed on different days and with different fertilization methods.The purpose of this study was to compare the neonatal and clinical outcomes between D4 and D5 ET, stratified by type of fertilization. Methods:This retrospective cohort study was conducted in the Xingtai Infertility Specialist Hospital between January 2018 and March 2023. A total of 1,622 fresh ART cycles met the inclusion criteria, including 1292 IVF transfers and 330 ICSI transfers. Conclusions: The clinical pregnancy and neonatal outcomes of D4 transfer were comparable to those of D5 transfer in fresh cycles. To improve clinical pregnancy outcomes and neonatal outcomes, D4 transfer should be given priority when fertilization method is IVF, when the E2 level on the hCG day is ≥3,807pg/ml, or when the LH value is ＜0.67 U/L.