A miscarriage (spontaneous abortion) is the loss of a fetus due to natural causes before 20 weeks of pregnancy.
Miscarriages may occur because of a problem in the fetus (such as a genetic disorder or birth defect) or in the woman (such as structural abnormalities of the reproductive organs, chromosomal abnormalities, infections, use of cocaine or alcohol, cigarette smoking, or an injury), but the cause is often unknown.
Bleeding and cramping may occur, particularly late in the pregnancy.
Doctors examine the cervix and usually do ultrasonography.
If any remnants of the pregnancy remain in the uterus after a miscarriage, they are removed.
A miscarriage occurs in about 10 to 15% of recognized pregnancies. Many more miscarriages are unrecognized because they occur before women know they are pregnant. About 85% of miscarriages occur during the first 12 weeks of pregnancy, and as many as 25% of all pregnancies end in a miscarriage during the first 12 weeks of pregnancy. Miscarriages are more common in high-risk pregnancies, particularly when women are not receiving adequate medical care (see High-Risk Pregnancy).