Cumulative live birth rate and perinatal outcomes of blastocyst versus cleavage-stage embryo transfer: A propensity score matching analysis

This study aims to investigate the effects of different transfer strategies (blastocyst vs cleavage-stage embryo) on the cumulative live birth rate (CLBR) and perinatal outcomes. In this propensity score matching (PSM) study, we evaluated the clinical data of 683 oocyte retrieval cycles performed using in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) from June 2017 to December 2022. The primary outcome was CLBR. Secondary outcomes were clinical pregnancy, implantation, live birth, multiple pregnancy, abortion (<28 weeks), ectopic pregnancy, preterm birth (<37 weeks), stillbirth, pregnancy complications, gestational age, birth weight, sex ratio, and birth defects in newborns. After PSM, compared to the cleavage-stage embryo transfer group in fresh embryo transfer cycles, the number of embryos transferred was lower, implantation rate was higher, and multiple pregnancy rate was lower in the blastocyst transfer group. In frozen-thawed embryo transfer cycles, the number of embryos transferred was lower, and clinical pregnancy rate, implantation rate and live birth rate were higher in the blastocyst transfer group. The CLBR was higher, and the multiple pregnancy rate was lower in the blastocyst transfer group. There was no statistically significant difference in perinatal outcomes between the 2 groups. Logistic regression analysis showed that CLBR was positively affected by the number of frozen embryos, and blastocyst transfer increased the CLBR. We conclude that blastocyst transfer is beneficial for improving CLBR and reducing multiple pregnancy rate.