Treatment with 17 alpha-hydroxyprogesterone caproate did not reduce the rate of preterm birth in women with twin gestations. (ClinicalTrials.gov number, NCT00099164 [ClinicalTrials.gov].).

Objective To assess whether 17 alpha-hydroxyprogesterone caproate reduces the rate of preterm birth in women carrying triplets. Methods We performed this randomized, double blinded, placebo controlled trial in 14 centers. Healthy women with triplets were randomized to weekly intramuscular injections of either 250 mg of 17 alpha-hydroxyprogesterone caproate or matching placebo, starting at 16-20 weeks and ending at delivery or 35 weeks of gestation. The primary study outcome was delivery or fetal loss prior to 35 weeks. Results One hundred thirty-four women were randomized, 71 to 17 alpha-hydroxyprogesterone caproate and 63 to placebo; none were lost to followup. Baseline demographic data were similar in the two groups. The proportion of women experiencing the primary outcome (a composite of delivery or fetal loss prior to 35 0/7 weeks) was similar in the two treatment groups : 83% of pregnancies in the 17 alpha-hydroxyprogesterone caproate group and 84% in the placebo group, relative risk (RR) 1.0, 95% confidence interval (CI) 0.9 to1.1. The lack of benefit of 17 alpha-hydroxyprogesterone caproate was evident regardless of the conception method or whether a gestational age cut off for delivery was set at 32 or 28 weeks. Conclusion Treatment with 17 alpha-hydroxyprogesterone caproate did not reduce the rate of preterm birth in women with triplet gestation.