Reducing the Rate of Prematurity

Reducing the Rate of Prematurity

Progesterone shows promise.

The rate of prematurity (birth before 37 weeks of gestation) continues to increase in the U.S., in part because of assisted fertilization. Preventing prematurity, particularly birth before 34 weeks, has been the subject of intensive research.

In a multisite, randomized, double-blind clinical trial, investigators used transvaginal ultrasound to screen 24,620 women at 20 to 25 weeks of gestation; 413 women with a cervical length of less than 15 mm received vaginal progesterone (200 mg at night) or placebo from 24 to 34 weeks of gestation. Women who received progesterone were significantly less likely than women in the placebo group to deliver an infant before 34 weeks of gestation (19.2% vs. 34.4%).

In another multisite, randomized, double-blind clinical trial, 655 women with twin gestations received either weekly intramuscular injections of progesterone (250 mg) or placebo, beginning at 16 to 20 weeks of gestation and ending at 35 weeks. No significant differences between groups were noted in the incidence of delivery or fetal death before 35 weeks (41.5% and 37.3% in the progesterone and placebo groups, respectively) or the rate of prespecified serious adverse fetal or neonatal outcomes (20.7% vs. 18.4%, respectively).

Comment: The results of the first study indicate that identifying and preventing premature delivery in high-risk women is possible, although widespread screening would be necessary to substantially affect rates of prematurity. The results of the second study suggest that the etiology of prematurity in twin gestations is likely different from that of singleton gestations.

— Howard Bauchner, MD

Published in Journal Watch Pediatrics and Adolescent Medicine August 1, 2007