Oral Micronized Progesterone for Prevention of Preterm Birth

Abstract

Support for the use of progesterone to prevent premature birth is provided by randomized controlled trials and meta-analyses. Intramuscular administration of 1 progesterone formulation, 17 alpha-hydroxyprogesterone caproate, has shown promise in trials, but administration by this route is painful and patient compliance may be reduced because of the need for medical assistance. Only a few studies have investigated the oral and vaginal routes using micronized progesterone. Vaginal administration can be associated with an unpleasant vaginal discharge, which may diminish its acceptability. This randomized, double-blind, placebo-controlled trial evaluated the efficacy, safety, and adverse effects of oral micronized progesterone (OMP) to prevent preterm birth in 150 women with a history of premature birth at an urban hospital in India between 2005 and 2006. The study subjects were randomized to receive either 100 mg of OMP (n = 75) or placebo (n = 75) twice daily from enrollment (18-24 weeks) until 36 weeks or delivery, whichever occurred first. The patients and medical staff were blinded to the study medication allocation. The proportion of women who had a preterm delivery was significantly lower in the OMP group compared with the control group (39.2% [n = 29] vs. 59.5% [n = 44], P 24 hours (P < 0.001), and Apgar scores at 1 and 10 minutes (P < 0.001). Fewer neonatal deaths occurred in the OMP group than the control group (3 vs. 7), but the difference was not statistically significant (P = 0.19). Adverse effects were minimal in both treatment groups. These findings demonstrating significant short-term benefits of OMP treatment in women at high risk of preterm birth are consistent with data from previous studies using intramuscular progestins and vaginal micronized progesterone.