Do Progesterone Injections Prevent Recurrent Preterm Birth?

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Summary and Comment

Do Progesterone Injections Prevent Recurrent Preterm Birth?

In this placebo-controlled study, 17P injections reduced rates of preterm delivery in high-risk women.

Results from some studies have suggested that 17 ${alpha}$ -hydroxyprogesterone caproate (17P) reduces the incidence of preterm delivery. In this study, funded by the National Institute of Child Health and Human Development, women at 19 U.S. clinical centers were randomized to receive weekly injections of 17P (n=310) or placebo (castor oil; n=153), beginning at 16-20 weeks' gestation and continuing until 36 weeks' gestation or delivery. All participants had histories of spontaneous preterm labor in a previous pregnancy.

17P injections significantly reduced the rate of preterm delivery at less than 37 weeks' gestation (36.3% vs. 54.9% with placebo). Similar risk reductions were noted for deliveries at less than 35 or 32 weeks' gestation. Necrotizing enterocolitis, intraventricular hemorrhage, and the need for supplemental oxygen occurred significantly less frequently among infants born to 17P recipients. Although neonatal mortality was substantially lower with 17P treatment than with placebo, this difference did not achieve statistical significance. Rates of chorioamnionitis, neonatal sepsis, and birth defects were not higher with 17P treatment.

Comment: The efficacy of 17P in preventing preterm delivery in these high-risk women is gratifying. Cautions apply, however: First, as the authors point out, this study did not assess the efficacy of 17P in preventing preterm delivery in lower-risk women; given that most preterm deliveries occur in women without antecedent preterm deliveries, this caveat assumes importance. A second concern, pointed out by an editorialist, is that 17P is not readily available in the U.S. Notwithstanding these limitations, this study represents an important step forward in combating the main cause of perinatal mortality in the U.S.

— Andrew M. Kaunitz, MD

Published in Journal Watch Women's Health August 19, 2003