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 or the woman (such as structural abnormalities, infections, certain disorders, 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.

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.

Causes

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:

• Structural abnormalities of the reproductive organs, such as a double uterus or an incompetent cervix, which tends to open (dilate) as the uterus enlarges
• Use of substances such as cocaine, alcohol, and tobacco (in cigarette smoking)
• Severe injuries
• Infections such as a cytomegalovirus infection or rubella
• An underactive thyroid gland (hypothyroidism) if the condition is severe or poorly controlled
• Diabetes if it is severe or poorly controlled
• Connective tissue disorders, such as systemic erythematosus lupus (lupus)

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.

Symptoms

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.

Did You Know... Many miscarriages are unrecognized because they occur before women know they are pregnant. About 20 to 30% of pregnant women have some bleeding at least once during the first 20 weeks of pregnancy.

Diagnosis

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.

Treatment

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 oxytocinSome Trade Names
PITOCIN
) may be given intravenously. OxytocinSome Trade Names
PITOCIN
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.

• Grief: Grief for a loss is a natural response and should not be suppressed or denied. Talking about their feelings with another person may help women deal with their feelings and gain perspective.
• Guilt: Women may think that they did something to cause the miscarriage. Usually, they have not. Women may recall taking a common over-the-counter drug early in pregnancy, drinking a glass of wine before they knew they were pregnant, or doing another everyday thing. These things are almost never the cause of a miscarriage, so women should not feel guilty about them.
• Anxiety: Women who have had a miscarriage may wish to talk with their doctor about the likelihood of a miscarriage in subsequent pregnancies and be tested if needed. Although having a miscarriage increases the risk of having another one, most women who have a miscarriage do not have problems in subsequent pregnancies.

Understanding the Language of Loss
Doctors may use the term abortion to refer to a miscarriage (spontaneous abortion) that occurs before 20 weeks of pregnancy as well as to intentional termination of pregnancy (induced abortion) for medical or other reasons. After 20 weeks of pregnancy, delivery of a fetus that has died is called a stillbirth. Terms for abortion include the following: Therapeutic (induced) abortion: An abortion that is brought about by medical means (drugs or surgery) because the woman's life or health is endangered or the fetus has major abnormalities Threatened abortion: Bleeding or cramping during the first 20 weeks of pregnancy, indicating that the fetus may be lost Inevitable abortion: Pain or bleeding with opening (dilation) of the cervix, indicating that the fetus will be lost Complete abortion: Expulsion of all of the fetus and placenta in the uterus Incomplete abortion: Expulsion of only part of the contents of the uterus Missed abortion: Retention of a dead fetus in the uterus Septic abortion: Infection of the contents of the uterus before, during, or after an abortion

Last full review/revision December 2008 by Edmund F. Funai, MD