Pregnancy, microchimerism and autoimmunity: an update

The presence of a small population of cells or DNA in one individual that derives from another genetically distinct person is referred to as microchimerism; this process may occur in course of pregnancy from mother to fetus, and vice versa. The clinical similarities between some features of autoimmune diseases and the chronic graft versus host disease, the increased incidence of autoimmune diseases observed in women after childbearing age, and the long-term persistence of microchimerism have raised the hypothesis that microchimerism could be involved in the pathogenesis of autoimmune diseases. To assess the possible relationship between pregnancy and the incidence of systemic sclerosis we performed a hospital-based case-control study. Our results, indicating a reduced risk for systemic sclerosis in women who had been pregnant in comparison with women who had not, seem to indicate that pregnancy is not a risk factor for systemic sclerosis.