What Is It?
A miscarriage is a loss of a pregnancy. The term is generally used when the loss occurs before 20 weeks of gestation. Other terms that are used for such losses include spontaneous abortion and early pregnancy failure.
About 15% to 20% of known pregnancies end in a miscarriage. Most miscarriages happen before the pregnancy is 12 weeks along. In the first several weeks of a pregnancy, a miscarriage sometimes happens because a fertilized egg did not properly form a fetus. In many cases, the activity of the fetal heart stopped days or weeks before the symptoms of miscarriage began.