A miscarriage, or spontaneous abortion, is the loss of a pregnancy before the embryo or fetus can survive. Miscarriage affects 10% to 15% or more of all pregnancies. A complete miscarriage occurs before 20 weeks of pregnancy (counting from the first day of the last normal period). Most miscarriages occur before 6 weeks or after 14 weeks of gestation. An incomplete miscarriage is the loss of some, but not all, of the elements of the pregnancy. When membranes (bag of waters) break or dilation (widening) of the cervix takes place during the first half of pregnancy, the term is inevitable miscarriage, and women lose the pregnancy. In a missed miscarriage, the uterus (womb) keeps the failed pregnancy for several weeks. A threatened miscarriage is a pregnancy in which symptoms such as bleeding or cramping indicate that a miscarriage is possible (but not automatic).
Separation of the fetus and placenta from the wall of the uterus leads to a miscarriage. Almost all miscarriages during the first 3 months of pregnancy (first trimester) occur because of an abnormal fetus. More than half of these fetuses have problems in the genes, which would cause major birth defects. The risk of a miscarriage increases with mother’s age above 35 years. Miscarriage during the second trimester (fourth through sixth months) is usually related to a problem in the woman. Such problems include chronic illness (such as diabetes, high blood pressure, or thyroid disease), infection, abnormal female organs (fibroids in the uterus), and drug use (such as tobacco and cocaine).
Exercising, working, and having sex don’t normally cause miscarriages, unless a woman is already at high risk for this condition.
Vaginal bleeding and cramping in the lower abdomen (belly) are the most common symptoms. Up to 40% of women may have mild symptoms but then have perfectly healthy pregnancies.
The health care provider can check the possibility of a miscarriage by a vaginal or ultrasound examination. Levels of certain pregnancy-related hormones may be measured, but they don’t always prove that a problem exists.
When a complete loss of pregnancy occurs, you and your body may only need to get back to normal before you try to become pregnant again. For an incomplete loss of pregnancy, the health care provider may prescribe medicines to complete the process or may remove tissues (by a simple surgical procedure called dilation and curettage, or D&C).
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