Abstract:  The unexplained recurrent miscarriage is a research hotspot in the worldwide medicine, and the immune factors of recurrent abortion have been presently focused. The complement system, as an important component of innate immunity, plays a complex and delicate role in pregnancy. A certain extent of activation of complement components is necessary for the normal development of the fetus and pregnancy appendages during pregnancy. The excessive activation of complement system on the maternal fetal interface can lead to embryo loss by the multiple mechanisms of placental development defect, inflammatory injury, and disorder of specific cellular immune. Therefore, dysfunction or excessive activation of the complement system is a risk factor for recurrent miscarriage. In this review, we reviewed the study progress of complement system in normal pregnancy and recurrent spontaneous abortion, in order to provide a feasible reference for the immunotherapy of recurrent miscarriage.

Key words: Complement system proteins, Abortion, habitual, Complement C3, Complement C5, Antibodies, antiphospholipid; , Immunity, cellular, Review