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Preterm Labor and Delivery

En Español (Spanish Version)

Main | Risk Factors | Symptoms | Diagnosis | Treatment | Medications | Surgery | Other Treatments | Screening | Reducing Your Risk | Talking to Your Doctor | Resource Guide

Preterm labor , or premature labor, is labor that occurs between the 20th and 37th week of pregnancy. A full-term pregnancy lasts 38-42 weeks. True labor includes both uterine contractions and cervical changes. Preterm labor can lead to preterm delivery. Babies who are born before 37 weeks are premature.

Fetus at 24 Weeks

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Preterm labor does not always lead to preterm delivery. Preterm labor can sometimes be stopped with a combination of medication and rest. If preterm labor cannot be stopped, your doctor will try to delay delivery. During this delay, you may be given corticosteroids to speed up the baby’s lung development. You may also be brought to a hospital with a neonatal intensive care unit (NICU).

Preterm birth is the number one cause of perinatal sickness and death. About 11% to 12% of births in the United States are premature; this translates to one in every eight births. Preterm babies have less time to develop in the womb. As a result, they are at higher risk of medical problems. They are also at greater risk for death than babies born full term. The earlier a baby is born, the greater the risks. Babies born before 28 weeks are at greatest risk for health and developmental issues. These issues include:

Babies born between 28 and 32 weeks are at lower risk for complications, compared to those born prior to 28 weeks. Those born between 32 and 35 weeks usually have only short-term medical problems. The outlook for all preterm infants continues to improve with medical advances.

Often, the cause of preterm labor is not clear. However, several factors have been identified that increase the risk. It is essential for all pregnant women to know the signs of preterm labor. The quicker you are able to respond to these signs, the better chance that your doctor can delay or prevent preterm delivery.

What are the risk factors for preterm labor and delivery? | What are the symptoms of preterm labor? | How is preterm labor diagnosed? | What are the treatments for preterm labor? | Are there screening tests for preterm labor? | How can I reduce my risk of preterm labor and delivery? | What questions should I ask my doctor? | Where can I get more information about preterm labor and delivery?



  • Late-Preterm Infants. The American College of Obstetricians and Gynecologists. Committee Opinion No. 404, April 2008. Available at: (Reaffirmed 2011)
  • Prematurity. EBSCO DynaMed website. Available at: Updated April 18, 2013 . Accessed April 23, 2013.
  • Preterm labor. EBSCO DynaMed website. Available at: Updated March 15, 2013 . Accessed April 23, 2013.
  • Preterm labor and birth. March of Dimes website. Available at: Updated September 2012. Accessed April 23, 2013.
  • Preterm labor and birth: overview. National Institute of Child Health & Human Development website. Available at: Updated April 3, 2013. Accessed April 23, 2013.
  • Preterm labor. The American College of Obstetricians and Gynecologists website. Available at: Accessed April 23, 2013.

Last reviewed March 2015 by Andrea Chisholm, MD

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This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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