Since 1978, in the first decades of in vitro fertilization (IVF), the use of ovarian hyperstimulation allowed for the development and transfer of multiple embryos. As IVF technology improved, the number of multiple pregnancies increased, which led to gradual reduction in the number of embryos that were transferred. Embryo freezing (vitrification) was recommended to allow subsequent transfer if the fresh cycle was unsuccessful. However, experimentation has continued to improve pregnancy outcomes. We discuss here the significance of frozen embryo transfer cycle and the impact of uterine and peripheral immunity dominated by NK cells and regulatory T cells and human chorionic gonadotropin on pregnancy outcome in this innovative mode of IVF therapy.

中文翻译：

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在冷冻胚胎移植周期中改善妊娠结果的新预测和治疗选择。

自 1978 年以来，在体外受精 (IVF) 的最初几十年中，卵巢过度刺激的使用允许多个胚胎的发育和移植。随着试管婴儿技术的进步，多胎妊娠的数量增加，导致移植的胚胎数量逐渐减少。如果新鲜循环不成功，建议进行胚胎冷冻（玻璃化）以进行后续转移。然而，实验继续改善妊娠结果。我们在此讨论冷冻胚胎移植周期的重要性以及由 NK 细胞、调节性 T 细胞和人绒毛膜促性腺激素主导的子宫和外周免疫对这种创新的 IVF 治疗模式中妊娠结局的影响。