Abstract: Blastocyst implantation is a critical stage in the pregnancy process, including apposition, adhesion and invasion of blastocysts in the endometrium. The blastocyst is a semi-allogeneic transplant for the uterus. The successful implantation dependents on the immune tolerance established and maintained by maternal immune cells located in the uterus. As the second largest immune cell group at the maternal-fetal interface, macrophages play a critical role in establishing and maintaining maternal-fetal immune tolerance and remodeling tissue and spiral arteries. Recent studies have found that abnormal differentiation or dysfunction of macrophages is significantly correlated with pathological pregnancy. Thus, studies on the types and functions of decidual macrophages will help us to improve the diagnosis and treatment of pathologic pregnancy. This review is mainly focused on research progresses in the derivation and classification of macrophages at the maternal-fetal interface as well as the roles of the macrophages in blastocyst implantation and pathological pregnancy.

Key words: Macrophages, Embryo implantation, Pregnancy complications, Maternal-fetus interface, Immune regulation