Purpose

To determine whether maternal age has an impact on monozygotic twinning (MZT) rates in women undergoing single embryo transfer (SET).

Methods

This is a retrospective cohort study analyzed for the incidence of MZT of all clinical pregnancies after a single embryo transfer was carried out between 2014 and 2018. The effect of different assisted reproductive technology (ART) parameters on the incidence of MZT was evaluated.

Results

There were a total of 8459 cycles resulting in pregnancy during the study period. Of these pregnancies, 8236 were singletons and 223 were MZT. The preterm birth rate, miscarriage rate, and cesarean section rate were higher in MZT. Birth weight and gestational age at delivery were lower and smaller. In the univariate analysis, the risk of MZT was decreased with frozen embryo transfer (ET). A nonlinear relationship was observed between maternal age and MZT. A negative relationship between maternal age and MZT was observed in the patients’ age ≥ 36 years.

Conclusion

Advanced maternal age was associated with a lower rate of MZT. A threshold female age of 36 years existed for lower MZT.

中文翻译：

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单胚胎移植后母亲年龄与胚胎分裂有关：一项回顾性队列研究

目的

确定母亲年龄是否对接受单胚胎移植 (SET) 的女性的单卵双胞胎 (MZT) 率有影响。

方法

这是一项回顾性队列研究，分析了 2014 年至 2018 年间进行单胚胎移植后所有临床妊娠的 MZT 发生率。评估了不同辅助生殖技术 (ART) 参数对 MZT 发生率的影响。

结果

在研究期间共有 8459 个周期导致怀孕。在这些怀孕中，8236 人是单胎，223 人是 MZT。MZT的早产率、流产率和剖宫产率较高。分娩时的出生体重和胎龄越来越小。在单变量分析中，冷冻胚胎移植 (ET) 降低了 MZT 的风险。在母亲年龄和 MZT 之间观察到非线性关系。在≥36岁的患者中观察到母亲年龄与MZT呈负相关。

结论

高龄产妇与较低的 MZT 发生率相关。存在较低 MZT 的阈值女性年龄为 36 岁。