Oral micronized progesterone for prevention of preterm birth

Abstract Objective To evaluate oral micronized progesterone (OMP) to prevent preterm birth (PTB). Methods A randomized, double‐blind, placebo‐controlled trial of 150 women with at least one PTB who received 100 mg of OMP or placebo twice a day from recruitment (18–24 weeks) until 36 weeks or delivery. Results PTB occurred in 29 (39.2%) women in the OMP group (n = 74) compared with 44 (59.5%) in the control group (n = 74, P = 0.002). Mean gestational age at delivery was higher in the OMP group (36.1 vs 34.0 weeks, P < 0.001). Fewer preterm births occurred between 28 and 31 weeks plus 6 days in the OMP group (RR 0.20; 95% CI, 0.05–0.73, P < 0.001). Neonatal age at delivery (34 vs 32 weeks, P < 0.001), birth weight (2400 vs 1890 g, P < 0.001), NICU stay (> 24 h, P < 0.001), and Apgar scores ( P < 0.001) were more favorable in the OMP group, and fewer neonatal deaths occurred (3 vs 7, P = 0.190). Conclusion OMP reduced the risk of PTB between 28 and 31 weeks plus 6 days, NICU admissions, and neonatal morbidity and mortality in high risk patients.