Miscarriage, the commonest complication of pregnancy, is the spontaneous loss of a pregnancy before the fetus has reached viability. The term therefore includes all pregnancy losses from the time of conception until 24 weeks of gestation. Recurrent miscarriage, defined as 3 or more consecutive pregnancy losses, affects about 1% of couples; when defined as 2 or more losses, the scale of the problem increases to 5% of all couples trying to conceive. [From OMIM]