Pregnancy and perinatal outcomes after day 5 versus day 6 blastocyst‐stage embryo transfer: A systematic review and meta‐analysis

作者：Wenhui Hou, Ziyi Wang, Tianrui Wen, Yuanlin Ma, Manman Lu, Xiuli Fan, Feifei Zhao · 发表于：Acta Obstetricia Et Gynecologica Scandinavica · 年份：2025 · DOI：10.1111/aogs.70090 · 研究领域：Reproductive Biology and Fertility、Assisted Reproductive Technology and Twin Pregnancy、Ovarian function and disorders

INTRODUCTION: Embryo transfer at the blastocyst stage has become popular in assisted reproductive technology, but it is still a challenge for embryologists to select the embryos with the highest implantation potential. We aimed to investigate whether blastocyst development speed and blastocyst quality affect pregnancy and perinatal outcomes in single frozen-thawed blastocyst transfer (SFBT) cycles. MATERIAL AND METHODS: We therefore conducted a meta-analysis to compare the pregnancy and perinatal outcomes after day 5 versus day 6 SFBT. Pregnancy and perinatal outcomes of SFBT included HCG positive rate, clinical pregnancy rate (CPR), live birth rate (LBR), miscarriage rate (MR), multiple pregnancy rate (MPR), ongoing pregnancy rate (OPR), ectopic pregnancy rate (EPR), mean birth weight, low birth weight (LBW) rate, rate of macrosomia, mean gestational age at birth, preterm birth rate, birth defects rate, and sex ratio (female/male). RESULTS: A total of 106 316 participants were included in this meta-analysis and were assigned to the D5 (n = 66 329) and D6 (n = 39 987) SFBT groups. Pooled analysis showed that the D5 SFBT group had a higher HCG positive rate (RR 1.24, 95% CI 1.14-1.34), CPR (RR 1.28, 95% CI 1.22-1.34), OPR (RR 1.36, 95% CI 1.21-1.53), LBR (RR 1.39, 95% CI 1.32-1.47), and a lower MR (RR 0.78, 95% CI 0.73-0.83) than the D6 SFBT group. No significant difference was observed between the D5 and D6 SFBT groups in other pregnancy and perinatal outcomes. Subgroup analy...