OBJECTIVEThis review aimed at understanding pregnancy-induced changes in the maternal immune response and mechanisms for the establishment of feto-maternal tolerance.

DATA SOURCESArticles cited in this review were obtained from PubMed in English from 2000 to 2014, and the search string included keywords such as feto-maternal tolerance, dendritic cells, macrophage, T regulatory cells, natural killer cells, cytokines and hormone.

STUDY SELECTIONArticles regarding altered maternal immune response, including the proliferation and differentiation of the altered cells, and the production of cytokines and regulation of hormones in the feto-maternal interface were retrieved, reviewed and analyzed.

RESULTSThe changes in immune cells and cytokines in the local uterine microenvironment and peripheral blood are correlated with the establishment of feto-maternal tolerance. The endocrine system regulates the maternal immune system, promoting modifications during pregnancy. In these regulatory networks, every factor is indispensible for others.

CONCLUSIONSThe integration and balance of these immune factors during pregnancy give rise to an environment that enables the fetus to escape rejection by the maternal immune system. This progress is complicated, and needs more comprehensive exploration and explanation.