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3: Prevention of preterm delivery after successful tocolysis in preterm labour by 17 alpha-hydroxyprogesterone caproate: a randomised controlled trial

      Objective

      Several small trials have suggested that progesterone might reduce the risk of preterm delivery among women with preterm labour arrested by tocolysis. This trial sought to test that hypothesis.

      Study Design

      This open-label multicentre randomised controlled trial took place at 13 French university hospitals and included women with singleton pregnancies admitted at 24+0 through 31+6 weeks of gestation with a cervical length <25 mm for an episode of preterm labour that was then successfully arrested by tocolytic treatment. A course of betamethasone 12 mg, repeated after 24 hours, was given intramuscularly in all patients. Women were randomly assigned (by a centralised, computer-generated randomisation process) in a 1:1 ratio to receive either 500 mg of intramuscular 17 alpha-hydroxyprogesterone caproate (17P), started after tocolysis ended and repeated twice weekly until 36 weeks or until preterm delivery, or no treatment with 17P. Additional management in the two arms was left to the discretion of the attending physician, except that progesterone was not allowed in the control group. The primary outcome was time from randomisation to delivery, assessed according to the intention-to-treat principle.

      Results

      A total of 188 women were randomised. The two groups were similar with respect to baseline characteristics. Outcome data were available for 184 women. There was no significant difference between the 17P and control groups in median [Q1-Q3] time to delivery (64 [42-79] and 67 [46-83] days, respectively; mean difference, -2; 95% confidence interval, -9 to +6) or in the rates of delivery before 37 (39% and 38%, p>0.99), 34 (16% and 20%, p=0.57), or 32 (9% vs 14%, p=0.35) weeks of gestation. Finally, rates of adverse perinatal outcomes did not differ significantly between the groups.

      Conclusion

      Biweekly injections of 500 mg of 17P did not prolong pregnancy significantly in women with an episode of preterm labour successfully arrested by tocolytic treatment.