Estimated Effect of 17 Alpha-Hydroxyprogesterone Caproate on Preterm Birth in the United States

Petrini, Joann R. PhD, MPH*†; Callaghan, William M. MD, MPH‡; Klebanoff, Mark MD, MPH§; Green, Nancy S. MD*†; Lackritz, Eve M. MD‡; Howse, Jennifer L. PhD*; Schwarz, Richard H. MD¶; Damus, Karla RN, PhD*†∥

doi: 10.1097/01.AOG.0000150560.24297.4f
Original Research

OBJECTIVE: A multicenter, randomized placebo-controlled trial among women with singleton pregnancies and a history of spontaneous preterm birth found that weekly injections of 17 alpha-hydroxyprogesterone caproate (17P), initiated between 16 and 20 weeks of gestation, reduced preterm birth by 33%. The current study estimated both preterm birth recurrence and the potential reduction in the national preterm birth rate.

METHODS: Using 2002 national birth certificate data, augmented by vital statistics from 2 states, we estimated the number of singleton births delivered to women eligible for 17P through both a history of spontaneous preterm birth and prenatal care onset within the first 4 months of pregnancy. The number and rate of recurrent spontaneous preterm births were estimated. To predict effect, the reported 33% reduction in spontaneous preterm birth attributed to 17P therapy was applied to these estimates.

RESULTS: In 2002, approximately 30,000 recurrent preterm births occurred to women eligible for 17P, having had a recurrent preterm birth rate of 22.5%. If 17P therapy were delivered to these women, nearly 10,000 spontaneous preterm births would have been prevented, thereby reducing the overall United States preterm birth rate by approximately 2%, from 12.1% to 11.8% (P < .001), with higher reductions in targeted groups of eligible pregnant women.

CONCLUSION: Use of 17P could reduce preterm birth among eligible women, but would likely have a modest effect on the national preterm birth rate. Additional research is urgently needed to identify other populations who might benefit from 17P, evaluate new methods for early detection of women at risk, and develop additional prevention strategies.


Although 17 alpha-hydroxyprogesterone caproate holds promise for preventing some preterm births, its effect on the national preterm birth rate is likely to be modest.

From the *National Office, March of Dimes, White Plains, New York; †Department of Obstetrics, Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, New York; ‡Maternal and Infant Health Branch, Division of Reproductive Health, Centers for Disease Control and Prevention, Department of Health and Human Services, Atlanta, Georgia; §Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland; ¶Department of Obstetrics and Gynecology, Maimonides Medical Center, Brooklyn, New York; ∥Department of Pediatrics and Cell Biology, Albert Einstein College of Medicine, Bronx, New York.

The authors thank Charles Denk, New Jersey Department of Health and Senior Services, and Wayne Schramm, Missouri Department of Health and Senior Services, for providing the data. We also thank Rebecca Russell and Michael Davidoff of the March of Dimes for their assistance with data analysis.

Address reprint requests to: Joann R. Petrini, March of Dimes, 1275 Mamaroneck Avenue, White Plains, NY. 10605; e-mail:

Received July 26, 2004. Received in revised form September 14, 2004. Accepted September 23, 2004.

© 2005 The American College of Obstetricians and Gynecologists