Preterm Labor

Medically reviewed by Drugs.com. Last updated on Apr 6, 2025.

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What is preterm labor?

Preterm (premature) labor occurs when the uterus contracts and your cervix opens earlier than normal. The cervix is the opening of your uterus. Preterm labor happens after the 20th week of pregnancy but before the 37th week. You may have premature rupture of membranes (PROM). PROM means your water broke before labor began. An early labor could cause you to have your baby before he or she is ready to be born.

What causes preterm labor?

The cause is sometimes unknown. The following may cause early labor:

• A large uterus or a short cervix can cause you to go into labor early.
• A chronic illness , such as high blood pressure, diabetes, or obesity, can cause early labor.
• An infection , such as a urinary tract infection or vaginal infection, can weaken the membranes (linings) of the amniotic sac around your baby. This could lead to premature rupture of the membranes and preterm labor.
• Problems with the placenta , such as placenta previa or placental separation, may cause preterm labor.
• Injury to your abdomen or uterus may also cause some cases of preterm labor.

What increases my risk for preterm labor?

• You are pregnant with 2 or more babies.
• You are under 17 or over 35 years of age.
• You get pregnant again less than 6 months after delivery.
• You had a preterm labor or preterm birth in the past.
• You did not have prenatal care.
• You smoke, drink alcohol, or use street drugs while pregnant.
• You are underweight. Too little weight gain during pregnancy may also increase your risk for early labor.

Drugs used to treat this and similar conditions

What are the signs and symptoms of preterm labor?

You may not know that you are having preterm labor. It is common to have preterm contractions (tightening and relaxing of the uterus) and not notice them. The following are signs and symptoms that suggest a preterm labor:

• Contractions that get stronger and closer together
• Changes in vaginal discharge, such as more discharge or discharge that is watery or bloody
• Low back pain
• Pressure in the lower abdomen
• Vaginal spotting or bleeding

How is preterm labor treated?

Early treatment may delay delivery. You may need any of the following:

• Bed rest may be recommended. You may need to lie on your left side, which improves circulation to your uterus and baby. Your healthcare provider will tell you when it is okay to get out of bed.
• Medicine may be given to stop contractions if your baby is not ready to be born. You may also need certain medicines if your preterm labor cannot be stopped and your healthcare provider thinks you will have your baby early. These medicines help your baby's lungs, brain, and digestive organs mature. They also help decrease your baby's risk of being born with cerebral palsy. If you have PROM, fluid from your vagina or rectum will be checked for a strep infection. You may be given antibiotics to prevent a strep infection during delivery. Antibiotics may also be used to prevent labor from starting. You may also need steroids to decrease the risk for complications due to preterm labor.

Call your local emergency number (911 in the US) if:

• You see or feel like there is something in your vagina.

When should I call my doctor?

• You have bright red, painless vaginal bleeding.
• Your symptoms do not get better or they get worse.
• Your water broke or you feel warm water gushing or trickling from your vagina.
• You have contractions that get stronger and closer together for more than 1 hour.
• You notice a decrease in your baby's movement.
• You have abdominal cramps, pressure, or tightening.
• You have a change in vaginal discharge.
• You have a fever.
• You have burning when you urinate or you are urinating less than is normal for you.
• You have questions or concerns about your condition or care.

Care Agreement

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