Some women are at greater risk for preterm labor than others (although, in most cases, the cause of preterm labor is unknown).  Women who have little or no prenatal care and those who have had preterm labor in the past are at increased risk.

A number of other risk factors have been linked to preterm labor.  There are also factors linked to the fetus that make preterm labor more likely.  For instance, too much fluid in the amniotic sac that surrounds the baby is a risk factor.  Problems with the placenta or certain birth defects also increases the risk.

You may be at risk for preterm labor if any of the following factors apply to you:

• You had preterm labor or preterm birth in a previous pregnancy.

• You are carrying more than one baby (twins, triplets, etc.)

• You have had one or more second-trimester induced abortions.

• You have an abnormal cervix (due to surgery, for example).

• You have an abnormal uterus.

• You have had abdominal surgery during the pregnancy.

• You have had serious infection while pregnant.

• You have had bleeding in the second or third trimester of your pregnancy.

• You are underweight or you weigh less than 100 pounds.

• You were exposed to DES (diethylstilbestrol, a drug given to many pregnant women in the 1950s and 1960s) as a fetus.

• You smoke or use drugs.

• You have had little or no prenatal care.