Abortion, Spontaneous

Spontaneous abortion is frequently caused by disease, stress, incompatibility genes or chromosomal aberrations. Various types of chromosomal defects were cytologically detected in 30-50% of the aborted fetuses. About 15-20% of the verified human pregnancies are aborted spontaneously and an estimated 22% of the abortions occur before pregnancy is clinically detected (5 weeks after the last menstruation). For placentation, the main source of steroid, the corpus luteum is replaced by appropriate supply of estrogens and progestin. Pregnancies of increased maternal level of cortisol are more likely to become aborted spontaneously during the first 3 weeks after conception (Nepomnaschy PA et al 2006 Proc Natl Acad Sci USA 103:3938). Different molecular mechanisms may account for abortion. Th2 lymphocytes and IL-10 and TGF-β may suppress incompatible paternal antigens in the fetus. Th1 cytokines, IL-2, INF-γ, and TNF-α may contribute to abortion. Indolamine 2,3-dioxygenase