Recurrent Miscarriage is an early pregnancy complication which affects about 1–3 % of child-bearing couples. The mechanisms involved in the occurrence of recurrent miscarriages are not clearly understood.

In the last decade Natural Killer cells have been studied in peripheral blood and uterus in order to determine if there are specific characteristics of Natural Killer cells associated with miscarriage. Different authors have described an increased number of uterine and peripheral blood Natural Killer cells in women with recurrent miscarriages compared to control women. However, its relationship with miscarriage has not been confirmed.

In patients with recurrent miscarriage a lack of inhibition of decidua Natural Killer cells can be observed, which leads to a more activated state characterized by higher levels of proinflammatory cytokines. In peripheral blood, it has been also reported a dysfunctional cytokine production by Natural Killer cells, with an increase of interferon-γ levels and a decrease of Interleukin-4.

Significant progress has been made in the last decade in understanding the biology of Natural Killer cells, including the identification of new receptors that also contribute to the activation and regulation of Natural Killer cells. In this review, we summarize the current progress in the study of Natural Killer cells in recurrent miscarriage.

复发性流产是一种早孕并发症，影响约 1-3% 的生育夫妇。反复流产发生的机制尚不清楚。

在过去的十年中，人们对外周血和子宫中的自然杀伤细胞进行了研究，以确定自然杀伤细胞是否具有与流产相关的特定特征。不同的作者描述了与对照女性相比，复发性流产女性的子宫和外周血自然杀伤细胞数量增加。但是，它与流产的关系尚未得到证实。

在复发性流产患者中，可以观察到对蜕膜自然杀伤细胞缺乏抑制，这导致以更高水平的促炎细胞因子为特征的更活化状态。在外周血中，也有报道称自然杀伤细胞产生功能失调的细胞因子，干扰素-γ 水平增加，白细胞介素 4 减少。

在过去十年中，在理解自然杀伤细胞的生物学方面取得了重大进展，包括识别也有助于自然杀伤细胞激活和调节的新受体。在这篇综述中，我们总结了自然杀伤细胞在复发性流产中的研究进展。