Single dose 17 alpha-hydroxyprogesterone caproate in preterm labor: a randomized trial.

OBJECTIVE: To evaluate the effect of a single 250-mg dose of 17 alpha-hydroxyprogesterone caproate (17-OHPC) intramuscularly as adjunct to nifedipine tocolysis in preterm labor. METHOD: Women diagnosed with threatened preterm labor between 22 and 35 weeks' gestation scheduled to receive nifedipine tocolysis and prophylactic antenatal corticosteroid were randomized to a single intramuscular injection of 250 mg of 17-OHPC or placebo saline in a double-blind fashion. Nifedipine tocolysis and corticosteroids were administered to all participants. Further management was otherwise carried out according to providers' discretion. Main outcome measures are delivery within 48 h and 7 days. RESULTS: Data were analyzed for the 56 participants randomized to 17-OHPC and 56 randomized to placebo. Delivery rates within 48 h were 11/54 (20.4%) versus 15/56 (26.8%) RR 0.76 (95% CI 0.38-1.51) and within 7 days were 13/52 (25.0%) versus 19/54 (35.2%) RR 0.71 (95% CI 0.39-1.29) for 17-OHPC and placebo groups, respectively, and were similar. Recruitment to delivery interval, gestation at delivery, delivery rate before 34 weeks' and 37 weeks' gestation, and neonatal outcomes were also similar. CONCLUSION: The results indicated that adjunctive single-dose 17-OHPC in combination with nifedipine tocolysis for threatened preterm labor did not delay delivery