VEGFA and polycystic ovary syndrome: Junovich et al. reported that endometrial CD16+ natural killer (NK) cells, interleukin-6, and vascular endothelial growth factor were good parameters for the diagnosis of unexplained infertility [43], whereas He et al. reported that NK cells might be a potential predictor of women with PCOS (AUC = 0.69) [44].