Progesterone for preventing preterm labor and delivery
During pregnancy, the placenta makes high levels of the hormone progesterone, which helps support the pregnancy. A drop in progesterone levels is thought to be one of many factors that help start labor contractions.1
Studies have shown that progesterone treatment in the second trimester helps lower the risk of preterm birth. This means that although some women still delivered prematurely, progesterone treatment helped more high-risk women carry their pregnancies longer than a placebo treatment did.2, 3 (In this case, "high-risk" meant that a woman had had at least one preterm birth in the past.)
In high-risk women, progesterone has been shown to reduce preterm birth.4
There is no evidence that progesterone treatment prevents early miscarriage.
Progesterone is a new treatment. And the type of progesterone used in this research, 17 alpha-hydroxyprogesterone caproate, is not available in all areas of the country.
The American College of Obstetricians and Gynecologists (ACOG) advises doctors to consider weekly progesterone injections only for women who are at high risk for preterm labor. This is based on studies of women who have had a previous spontaneous preterm birth (before 37 weeks).5 More research is needed before other high-risk women, such as those who already have signs of preterm labor or women who are pregnant with twins or more, can be considered for progesterone treatment.
- Da Fonseca EB, et al. (2003). Prophylactic administration of progesterone by vaginal suppository to reduce the incidence of spontaneous preterm birth in women at increased risk: A randomized placebo-controlled double-blind study. American Journal of Obstetrics and Gynecology, 188(2): 419–424.
- Meis PJ, et al. (2003). Prevention of recurrent preterm delivery by 17 alpha-hydroxyprogesterone caproate. New England Journal of Medicine, 348(24): 2379–2385.
- Mackenzie R, et al. (2006). Progesterone for the prevention of preterm birth among women at increased risk: A systematic review and meta-analysis of randomized controlled trials. American Journal of Obstetrics and Gynecology, 194: 1234–1242.
- Haas DM (2008). Preterm birth, search date June 2007. Online version of BMJ Clinical Evidence: htp://www.clinicalevidence.com.
- American College of Obstetricians and Gynecologists (2008). Use of progesterone to reduce preterm birth. ACOG Committee Opinion No. 419. Obstetrics and Gynecology, 112: 963–965.
Last Updated: January 14, 2009
Author: Sandy Jocoy, RN