Also known as spontaneous abortion, miscarriage is the loss of a fetus before 21 weeks of gestation.
Habitual abortion is defined as the spontaneous loss of three or more consecutive pregnancies. Habitual or recurrent abortion is a form of infertility. Couples who have had two or more miscarriages, or spontaneous abortions, have about a five percent chance that one member of the couple is carrying a chromosome problem that is contributing to the miscarriages.
A considerable proportion of pregnancies end in miscarriage.