Abstract: Fetal microchimerism（FMC）resides widely in woman′s body during pregnancy. Although the exact mechanism of FMC is not clear，in recent years several studies have been made which illustrate the influences of FMC on the maternal body.The abnormality of FMC may be related with complications of pregnancy and adverse pregnancy outcome，such as preeclampsia. FMC are also implicated in the pathogenesis of autoimmune diseases which usually occur to women and ameliorate during pregnancy. It has also been proposed that genetically disparate FMC may protect mother from some cancers，because it can offer new alleles for mother. FMC are often found at sites of maternal injury and may play an active role in regeneration of tissue injury. This article will summarize the influence of FMC on the maternal body.

Key words: Microchimerism, Pregnancy complications, Autoimmune diseases, Neoplasms, Pregnancy outcome