Preterm Labor


Preterm labor is labor that starts before 37 weeks. It can lead to early delivery. Babies born before 37 weeks are premature.


The cause is not always known. Sometimes it is caused by preterm premature rupture of membranes (PPROM). This is when the amniotic sac breaks before 37 weeks and labor has not started within 1 hour.

Amniotic Sac

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Risk Factors

This problem is more common in women who:

  • Are Black
  • Are pregnant with more than 1 baby
  • Used assistive reproductive technology to become pregnant
  • Are under the age of 16 years old

Some things that may raise the risk are:

  • Prior premature birth
  • Problems with the cervix
  • Certain infections
  • Substance use
  • Alcohol use
  • Mental health problems, such as depression or anxiety
  • Problems with the placenta or uterus
  • Vaginal bleeding
  • Birth defects in the fetus


Problems may be:

  • Belly cramps with or without diarrhea
  • Watery or bloody vaginal discharge
  • An increase in discharge
  • Dull pain in the lower back
  • Pressure in the pelvis and tightening in the thighs


You will be asked about your symptoms and health history. An exam will be done. This is often enough to make the diagnosis.


Treatment will depend on your baby's growth, especially the lungs. Labor may be allowed to go on in a baby that is more developed. The doctor may try to stop labor in a baby that is not developed enough.

Some ways this may be treated are with:

  • Tocolytics to try to delay labor for a few days
  • Corticosteroids to help the baby's lungs grow
  • Antibiotics to treat an infection


This problem cannot always be prevented. Early and regular prenatal care can help find and treat some problems before they happen.


American Congress of Obstetricians and Gynecologists
American Pregnancy Association


The Society of Obstetricians and Gynaecologists of Canada


American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol. 2016 Oct;128(4):e155-64, reaffirmed 2018.
Premature and preterm labor. American Pregnancy Association website. Available at:
...(Click grey area to select URL)
Accessed July 21, 2020.
Preterm labor. EBSCO DynaMed website. Available at: Updated November 14, 2019. Accessed July 21, 2020.
7/15/2016 DynaMed Systematic Literature Surveillance. Saccone G, Berghella V, et al. Celiac disease and obstetric complications: a systematic review and metaanalysis. 2016;214(2):225-234.
Last reviewed March 2020 by EBSCO Medical Review Board Elliot M. Levine, MD, FACOG
Last Updated: 3/16/2021

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