A miscarriage (spontaneous abortion) is the loss of a fetus due to natural causes before 20 weeks of pregnancy.
Miscarriage is a common end to a high-risk pregnancy. A miscarriage occurs in about 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.
Most miscarriages that occur during the first 12 weeks of pregnancy are thought to occur because something was wrong with the fetus, such as a birth defect or a genetic disorder.
The remaining 15% of miscarriages occur during weeks 13 to 20. For many of these miscarriages, no cause is identified. The rest result from problems in the woman, such as the following:
Rh incompatibility (when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood) also increases risk. Emotional disturbances and minor injuries are not linked with miscarriages.
A miscarriage is more likely for women who have had a miscarriage or preterm labor in a previous pregnancy. For women who have had three consecutive miscarriages during the 1st trimester, the chance of having another miscarriage is about 1 in 4.
A miscarriage is usually preceded by spotting or more obvious bleeding and a discharge from the vagina. The uterus contracts, causing cramps. However, about 20 to 30% of pregnant women have some bleeding at least once during the first 20 weeks of pregnancy. Fewer than half of these episodes result in a miscarriage.
Early in a pregnancy, the only sign of a miscarriage may be a small amount of vaginal bleeding. Later in a pregnancy, a miscarriage may cause profuse bleeding, and the blood may contain mucus or clots. Cramps become more severe until eventually, the uterus contracts enough to expel the fetus and placenta.
Sometimes the fetus dies but no symptoms of miscarriage occur. In such cases, the uterus does not enlarge. Rarely, the dead tissues in the uterus become infected before, during, or after a miscarriage. Such an infection may be serious, causing fever, chills, and a rapid heart rate. Affected women may become delirious, and blood pressure may fall.
If a pregnant woman has bleeding and cramping during the first 20 weeks of pregnancy, a doctor examines her to determine whether a miscarriage is likely. The doctor examines the cervix to determine whether it is dilating. If it is not, the pregnancy may be able to continue. If it is dilating, a miscarriage is very likely.
Ultrasonography is usually also done. It may be used to determine whether a miscarriage has already occurred or, if not, whether the fetus is still alive. If a miscarriage has occurred, ultrasonography can show whether the fetus and the placenta have been expelled.
If women have had several miscarriages, they may want to see a doctor before they try to become pregnant again. The doctor can check for genetic or structural abnormalities and for other disorders that increase the risk of a miscarriage. For example, an imaging test (such as hysteroscopy or hysterosalpingography) may be done to look for structural abnormalities. If identified, some causes of a previous miscarriage can be treated, making a successful pregnancy possible.
If the fetus is alive, bed rest may be advised to help reduce bleeding and cramping. If possible, the woman should not work but should stay off her feet at home. However, there is no clear evidence that bed rest is helpful. Refraining from sexual intercourse is advised, although intercourse has not been definitely connected with miscarriages.
If a miscarriage has occurred and the fetus and the placenta have been expelled, no treatment is needed.
If a miscarriage has occurred but some tissue from the fetus or placenta remains in the uterus, suction curettage (see Family Planning: Surgical Evacuation) is done to remove them.
If the fetus dies during the first 13 weeks but remains in the uterus, suction curettage is usually used to remove the fetus and the placenta.
If the fetus dies later in the pregnancy, a drug that can induce labor (such as oxytocin) may be given intravenously. Oxytocin stimulates the uterus to contract and expel the fetus. Afterward, suction curettage may be needed to remove pieces of the placenta. Alternatively, a procedure similar to suction curettage called dilation and evacuation (D & E) may be done. For D & E, labor does not need to be induced. However, this procedure may not be available because it requires special training.
Emotions After Miscarriage:
After a miscarriage, women may feel grief, sadness, anger, guilt, or anxiety about subsequent pregnancies.
Last full review/revision December 2008 by Edmund F. Funai, MD