17: Vaginal progesterone as maintenance treatment after an episode of preterm labor (PROMISE Study): a randomized, double blinded, placebo-controlled trial


      To demonstrate if maintenance treatment with vaginal progesterone after an arrested preterm labor reduces the incidence of preterm delivery before 34.0 or 37.0 pregnancy weeks.

      Study Design

      This was a prospective, randomized, double blind, multicenter clinical trial. 12 centers all over Spain were including women with single pregnancy and preterm labor successfully arrested, in whom decision of discharge was made, gestational age between 24.0-34.0 weeks and cervical length < 25mm. Women were randomly assigned (by a centralised computer-generated process) in a 1:1 ratio, stratified by two blocks of gestational week (24.0-30.6 and 31.0-33.6) and center. Intervention: women were allocated to one of the two arms: the study group received vaginal capsules of 200 mg progesterone and the control group received identical capsules containing placebo, once daily until delivery or 36.6 weeks gestation, whichever occurred first.


      A total of 265 women were included in the study. Last woman recruited was included in February 2012. Outcome data were available for 259 women: 127 women were randomized to the progesterone group and 132 to the placebo group. There were no significant differences between the progesterone and the placebo groups in terms of gestational age at delivery (weeks, mean (SD)): 37.1(5.2) vs 37.2(5.9), delivery < 34 weeks: 10/127 (7.9%) vs 12/132 (9.1%), p = 0.82, or delivery < 37 weeks: 38/127 (29.9%) vs 33/132 (25%), p = 0.40, respectively. Number of women recruited at 24.0-<31.0 and 31.0-33.6 weeks gestation, were 117 and 142 women, respectively. There were no differences either between progesterone and placebo groups when women < 31.0 weeks or 31.0-33.6 weeks were compared.


      200 mg of daily vaginal progesterone capsules administered as a maintenance treatment after an episode of preterm labor successfully arrested with tocolytic treatment, did not significantly prolong pregnancy.