Do uterine natural killer (uNK) cells contribute to female reproductive disorders?

The most abundant immune cells in the uterine decidua around the time of implantation and early placental development are the uterine natural killer (uNK) cells. Altered numbers of uNK cells have been associated with several human reproductive disorders, including recurrent miscarriage, recurrent implantation failure, uterine fibroids, sporadic miscarriage, fetal growth restriction and preeclampsia. Understanding of the function of uNK cells in non-pregnant and pregnant endometrium is now increasing; the potential contribution of altered numbers and function of uNK cells to reproductive disorders is the focus of this review.