%0 Journal Article %T Decidual Natural Killer Cells Are Essential for a Successful Pregnancy (Review) %A Ehab A. M. Elagab %A Majed Alshahrani %A Amin A. A. Elbadawi %A Abdullah I. Aedh %A Ahmed M. Osman %A Hanadi M. Osman %J Advances in Reproductive Sciences %P 73-90 %@ 2330-0752 %D 2022 %I Scientific Research Publishing %R 10.4236/arsci.2022.103008 %X Pregnancy is a complex physiological process involving several interconnected systems. Many researchers were concerned that the formation of a fetus with different genetic components may contradict the normal state of immunity, which attempts to reject and fight foreign bodies. This piqued the interest of biologists and immunologists, who set out to discover the immune system¡¯s composition and mode of response in the uterus. According to several studies, natural killer (NK) cells are present in a significant percentage that differs from what is seen in peripheral blood. As a result, several scientific studies have been conducted on uterine NK cells, investigating their types, characteristics, receptors, secretions, and interactions with the surrounding environment. Research has also indicated the capacity of uterine NK cells to strike a balance between eradicating uterine infections and effectively contributing to different phases of pregnancy. Various studies have shown that NK cell activity is intimately related to the success or failure of pregnancy. In this review, we describe the uterine NK cell subtypes; decidual (dNK) cells and endometrial NK cells (eNK) cells and their important role during different phases of pregnancy. %K Uterine NK Cells %K Decidual NK Cells %K Pregnancy %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=118110