Maternal immune system

The maternal immune system is a complex network of innate and adaptive immune cells and molecules that undergoes dynamic changes during pregnancy to accommodate and protect the developing fetus while maintaining defense against pathogens[1][2][4][5]. At the maternal-fetal interface, key players include decidual natural killer (NK) cells, macrophages, T cells, and other leukocytes, all of which are actively regulated by interactions with the placenta and trophoblast cells[2][5][7][9]. The system promotes tolerance to fetal antigens (which are partly paternal in origin) via immunoregulatory mechanisms such as induction of specialized uterine NK cells, polarization of macrophages toward anti-inflammatory phenotypes, modulation of T cell responses, and altered cytokine production[2][4][5]. Disruption or dysregulation of maternal immune adaptation may result in pregnancy complications such as preeclampsia, spontaneous abortion, or fetal growth restriction[5]. The maternal immune system is not a single defined molecule or receptor, nor a standard drug target, but rather a comprehensive collection of immune processes tailored for pregnancy adaptation[2][4][5].