Uterine natural killer cells dysregulation in idiopathic human preterm birth: a pilot study

To compare between uterine natural killer (uNK) cells in the placental samples of preterm birth and term labor.

Two-arm case-control study. This study included 60 participants divided into two groups. The first group included 30 cases of idiopathic spontaneous preterm labor and the other group included 30 women who delivered by a spontaneous term vaginal delivery and with no history of previous preterm labor.

There were no CD16^- CD56^bright uNK cells in either groups; CD16⁺ CD56^dim uNK cells were present in only 1 case out of 30 term delivery placentae (3.3%), whereas they were found in 21 cases out of 30 (70%) preterm placental samples with a significant statistical difference (p < 0.0001) and OR 67.667, 95% CI (7.95-575.69). CD16⁺CD56^dim uNK cells were found to be invading both the villi and the decidua in 11 cases (70%), whereas those cells were found invading only the villi in 10 cases (33.3%).

CD16⁺CD56^dim cells are expressed in both the decidua and the villi of patients with idiopathic preterm labor suggesting an association between uNK cells dysregulation and idiopathic human preterm labor.