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Progesterone and Preterm Labor

Can Progesterone Help Prevent Premature Labor and Birth?

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Updated October 16, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Progesterone can help prevent premature birth.

Progesterone injections can help prevent preterm labor.

Image copyright Peter Dazeley / Getty Images

Preventing Premature Birth With Progesterone

Premature birth is a tragedy that affects about 12% of US babies each year. NICUs have gotten very good at caring for preemies, but they're still at risk for complications of prematurity. While we're getting better at taking care of preemies, medical science is having a hard time figuring out how to stop babies from being born early in the first place. Progesterone is an old medication that has come back into favor for its ability to prevent premature labor in some women.

What is Progesterone?

Progesterone is a steroid hormone that is important to developing and maintaining a healthy pregnancy. It's been used for decades to prevent premature birth, but fell out of favor due to conflicting studies. Over the past several years, further study has shown that progesterone can indeed help to prevent premature labor in certain women.

Progesterone can be given in 3 ways: as a weekly injection, a daily vaginal medication, or a daily oral pill. Most of the research has focused on injected and vaginal progesterone, so those are the most common forms that doctors prescribe. 

Can Progesterone Prevent All Premature Births?

Progesterone has been well studied, and doctors have learned exactly what types of premature births the medication can help prevent.

  • Previous Preterm Birth: If you've had a premature baby, progesterone can help prolong your pregnancy and help you not to have another preemie. The effect is significant - weekly progesterone shots can help reduce your chances of another premature birth by about 18%.
  • Short Cervix: If you're at risk for premature birth, doctors may do an ultrasound to see if your cervix has begun to shorten. In women with a short cervix, progesterone is proven to help reduce your risk of delivering before 34 weeks by as much as 15%.

Although progesterone is very good at helping to prevent an early birth in women with a history of preterm labor or who have a short cervix, progesterone cannot help everyone. Progesterone is not helpful in the following situations:

  • Multiple Pregnancy: If you're carrying twins or more, progesterone can't help prevent premature labor. Premature labor with singletons and with multiples have different causes, and progesterone doesn't work to prevent the uterine stretching that often causes labor to start with multiples.
  • Medical Issues: Many babies are born early due to medical problems in the mother or the baby, such as preeclampsia, gestational diabetes, or genetic problems in the baby. These issues can be dangerous for mom or baby if pregnancy is prolonged, so progesterone won't be used.

Can Progesterone Help if Labor Has Already Started?

Sometimes labor starts early in women who didn't know they were at risk for premature birth. New research is focusing on whether progesterone can help prevent preterm birth after labor has already started. Only a few small studies have been completed, and the results are conflicting. Hopefully future research will show how best to use progesterone in these cases.

Sources:

Airkan, I., Barut, A., Harma, M., & Harma, I.M. (2011) "Effect of Progesterone as a Tocolytic and in Maintenance Therapy during Preterm Labor." Gynecologic and Obstetrical Investigations. 72,269-273.

Dodd, J., Jones, L., Flenady, V., Cincotta, R., & Crowther, C. (2013) "Prenatal Administration of Progesterone for Preventing Preterm Birth in Women Consisered to be at Risk for Preterm Birth." Cochrane Dadabase of Systematic Reviews. Issue 7.

Rozenberg, P. et al. (March 2012) "Prevention of Preterm Delivery After Successful Tocolysis in Preterm Labor by 17 alpha-hdroxyprogesterone caproate: A Randomized Control Trial." American Journal of Obstetrics & Gynecology. 206, e1-9.

Schmouder, V., Prescott, G., Franco, A., & Fan-Havard, P. (April 2013). "The Rebirth of Progesterone in the Prevention of Preterm Labor." The Annals of Pharmacotherapy. 47, 527-536.

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