What Is It? A miscarriage is a loss of a pregnancy. The term is
generally used when the loss occurs before the fetus might be
able to survive outside the womb, so before about 22 to 24 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. A common sign of
miscarriage is bleeding, although not all pregnancies with
bleeding end in miscarriage. In the years before ultrasound, a
miscarriage was diagnosed when a woman's body had expelled all
or some of the fetus, the placenta and the fluid surrounding the
baby. Today, ultrasound may identify pregnancy loss before the
body has begun the pro