Vaginal progesterone for the prevention of preterm birth in twin gestations: a randomized placebo-controlled double-blind study

ObjectiveThe purpose of this study was to investigate the use of vaginal progesterone for the prevention of preterm delivery in twin pregnancies.Study DesignWe conducted a prospective, randomized, double-blind, placebo-controlled trial that involved 390 naturally conceived twin pregnancies among mothers with no history of preterm delivery who were receiving antenatal care at a single center. Women with twin pregnancies between 18 and 21 weeks and 6 days' gestation were assigned randomly to daily vaginal progesterone (200 mg) or placebo ovules until 34 weeks and 6 days' gestation. The primary outcome was the difference in mean gestational age at delivery; the secondary outcomes were the rate of spontaneous delivery at <34 weeks' gestation and the rate of neonatal composite morbidity and mortality in the treatment and nontreatment groups.ResultsThe baseline characteristics were similar in both groups. The final analysis included 189 women in the progesterone group and 191 in the placebo group. No difference (P = .095) in the mean gestational age at delivery was observed between progesterone (35.08 ± 3.19 [SD]) and placebo groups (35.55 ± 2.85). The incidence of spontaneous delivery at <34 weeks' gestation was 18.5% in the progesterone group and 14.6% in the placebo group (odds ratio, 1.32; 95% confidence interval, 0.24-2.37). No difference in the composite neonatal morbidity and mortality was observed between the progesterone (15.5%) and placebo (15.9%) groups (odds ratio, 1.01; 95% confidence interval, 0.58-1.75).ConclusionIn nonselected twin pregnancies, vaginal progesterone administration does not prevent preterm delivery and does not reduce neonatal morbidity and death.