ORIGINAL RESEARCH article
Front. Endocrinol.
Sec. Reproduction
This article is part of the Research TopicAdvancing embryo transfer in assisted reproductive technologyView all articles
Cryopreservation duration does not affect pregnancy or neonatal outcomes in single high-quality blastocyst transfers: a multicenter retrospective study
Provisionally accepted
- 1Shandong University, Jinan, China
- 2Northwest Women and Children's Hospital, Xi'an, China
- 3Tongji Hospital Affiliated to Tongji University, Shanghai, China
- 4Xiamen University, Xiamen, China
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Objective: To study the effect of embryo cryopreservation duration on pregnancy and neonatal outcomes in women transferred with high-quality blastocyst during frozen embryo transfer (FET) cycles. Design: Multicenter Retrospective cohort study. Setting: Three tertiary-care academic medical centers. Patients: This retrospective study included a total of 24,101 women who underwent single high-quality blastocyst transfer during their first FET cycles at three tertiary academic medical centers between January 2016 and June 2023. Intervention(s): Women were categorized into two groups according to the duration of embryo cryopreservation: the short Cryo group consisted of 23,933 women with a storage time of 0–5 years, while the long Cryo group included 168 women with a storage time > 5 years. Women in the long Cryo group were matched to those in the short Cryo group using propensity score matching with a 1:4 ratio. Main Outcome Measure(s): The pregnancy outcomes and the neonatal outcomes. Result(s): After adjusting for potential confounding factors, no significant differences were observed between the two groups in pregnancy outcomes, including biochemical pregnancy (adjust odds ratio [aOR] 1.04, 95% confidence interval [CI], 0.70–1.56; P = 0.831), clinical pregnancy (aOR 1.10, 95% CI, 0.75–1.60; P = 0.638), ectopic pregnancy (aOR 2.15, 95% CI, 0.37–12.56; P = 0.394), miscarriage (aOR 0.95, 95% CI, 0.54–1.69; P = 0.871), and live birth (aOR 1.09, 95% CI, 0.76–1.55; P = 0.646). In addition, no significant differences were observed in neonatal outcomes, including very preterm birth, preterm birth, very low birth weight, low birth weight, high birth weight, birth weight, and gestational age. Conclusion(s): Our analysis found no evidence of significant associations between prolonged cryopreservation of high-quality blastocysts and adverse pregnancy or neonatal outcomes.
Keywords: cryopreservation duration, Frozen embryo transfer, High-quality Blastocyst, neonatal outcome, Pregnancyoutcome
Received: 11 Nov 2025; Accepted: 09 Feb 2026.
Copyright: © 2026 He, Xue, Li, Huang, Ren, Ma, Li, JIN and Shi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Tingting He
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