Research question

Does repeated cryopreservation process affect embryo implantation potential and neonatal outcomes of human embryos?

Design

This retrospective cohort study was conducted in the Reproductive Medicine Centre, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. All assisted reproductive technology (ART) cycles were carried out between January 2014 and December 2018. Preferentially matched participants were divided into three groups according to the times of embryo cryopreservation: the fresh group (n = 249), the cryopreservation group (n = 244) and the re-cryopreservation group (n = 216). Embryo implantation rate, live birth rate, miscarriage rate and neonatal complication rate were compared among these three groups.

Results

The embryo implantation rate, clinical pregnancy rate and live birth rate in the re-cryopreservation group were significantly lower, and the miscarriage rate also slightly increased. Logistic regression analysis indicated that embryos with repeated cryopreservation and lower trophectoderm scores were at higher risk of embryo implantation failure in single embryo transfer cycles (OR 1.79 and 1.56, respectively). No significant differences were observed in gender, gestational age, birthweight, neonatal abnormality and neonatal complications among the groups.

Conclusions

Our findings demonstrate the adverse effect of repeated cryopreservation on embryo implantation potential. The study offers embryologists and reproductive clinicians a warning of detrimental role of repeated cryopreservation. If unnecessary, it is strongly recommended to avoid repeated practice of vitrification and warming on embryos.

中文翻译：

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重复冷冻保存过程会损害胚胎植入潜力，但不会影响新生儿结局

研究问题

重复的冷冻保存过程是否会影响人类胚胎的胚胎植入潜力和新生儿结局？

设计

本回顾性队列研究在华中科技大学同济医学院附属同济医院生殖医学中心进行。所有辅助生殖技术（ART）周期均在 2014 年 1 月至 2018 年 12 月期间进行。 优先匹配的参与者根据胚胎冷冻保存的时间分为三组：新鲜组（n  = 249）、冷冻保存组（n  = 244 ) 和再冷冻保存组 ( n  = 216)。比较三组胚胎着床率、活产率、流产率和新生儿并发症发生率。

结果

再冻存组胚胎着床率、临床妊娠率和活产率显着降低，流产率也略有增加。Logistic 回归分析表明，重复冷冻保存和滋养外胚层评分较低的胚胎在单个胚胎移植周期中胚胎着床失败的风险较高（OR 分别为 1.79 和 1.56）。各组间在性别、胎龄、出生体重、新生儿畸形和新生儿并发症方面无显着差异。

结论

我们的研究结果证明了重复冷冻保存对胚胎植入潜力的不利影响。该研究向胚胎学家和生殖临床医生提供了重复冷冻保存有害作用的警告。如果没有必要，强烈建议避免重复对胚胎进行玻璃化和加热。