Neonatal and maternal outcomes following transfer of vitrified embryos compared with slow-frozen and fresh embryos: a retrospective study in singletons.

Authors

Yue Ying, Jianpeng Chen, Yun Huang, Xilin Shen, YiFeng Lin, Dan Zhang

Published in

BMC pregnancy and childbirth. Jul 04, 2026. Epub Jul 04, 2026.

Abstract

Embryo cryopreservation plays an essential role in assisted reproductive technology (ART). Vitrification has gradually replaced slow-freezing of embryos. In this study we investigated the effects of embryo vitrification on neonatal and maternal health.
The retrospective study involved 19,752 in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles performed at the Reproductive Medicine Center in Women's Hospital, School of Medicine, Zhejiang University between October 2014 and September 2019. 7707 singletons got live birth, among which 427 were born after transfer of vitrified embryos, 3737 slow-frozen and 3543 fresh. Neonatal and maternal outcomes of singleton liveborns following transfer of vitrified were compared with slow-frozen and fresh embryos. Logistic regression analysis was conducted to adjust for possible confounders.
Transfer of vitrified embryos was comparable with slow-frozen embryos in low birth weight, macrosomia, small/large for gestational age (SGA/LGA) and birth defects. When compared with transfer of fresh embryos, transfer of vitrified embryos was associated with a higher risk of hypertensive disorders in pregnancy (HDP) aOR 7.12 (3.82-13.06), postpartum hemorrhage (PPH) aOR 6.81 (3.15-14.48) and cesarean section aOR 1.67 (1.34-2.10). No statistical differences were found for birth defects. There was a rising trend in birth weight, fetal macrosomia and LGA, as well as a declining trend in LGA after transfer of vitrified embryos compared to fresh embryos, though no statistical differences were found for risks.
Transfer of vitrified embryos was comparable in birth weight and birth defects with slow-frozen embryos. When compared with fresh embryo transfer, transfer of vitrified embryos showed higher risks of HDP, PPH and cesarean section, and a rising trend in birth weight, which needs further follow-up.
IRB-20190052, 6th June 2019 retrospectively registered.

PMID:
42401823
Bibliographic data and abstract were imported from PubMed on 05 Jul 2026.

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