Abstract: Successful pregnancy is attributed to the maternal-fetal immune tolerance. Spontaneous abortion may be induced by intrauterine infection which can initiate the maternal immune system to reject the fetal. Toll-like receptors（TLRs）form the major family of pattern recognition receptors in the innate immune system and play an important role in maintaining normal pregnancy and promoting the development of spontaneous abortion because TLRs are involved in the innate immune responses against microorganisms at the maternal-fetal interface. The interaction between TLRs and invading pathogen can active the innate immune system to resist infection，at the same time，spontaneous abortion may be induced because the immune response may make microenvironment at the maternal-fetal interface change. At the maternal-fetal interface，inflammatory cytokines can be released imbalancedly，innate immune cells may be activated inappropriately，which may lead to trophoblast cells excessive apoptosis and eventually result in abortion. TLRs is also associated with antiphospholipid mediating thrombosis at the maternal-fetal interface and fetal loss.

Key words: Toll-like receptors, Spontaneous abortion, Immunity, Maternal-fetal interface, Inflammatory cytokines