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10: Maintenance nifedipine vs. placebo: A prospective, double blind trial

      Objective

      To test whether treatment with nifedipine after arrested preterm labor prolongs pregnancy and improves neonatal outcomes.

      Study design

      A prospective, randomized, double-blind, multi-center study was conducted. After successful tocolysis of preterm labor patients were randomized to 20 mg nifedipine or an identical-appearing placebo every 4-6 hours, and treatment was continued until 37 weeks. The primary outcome was attainment of 37 weeks gestation. Patients were included between 24 and 34 weeks if they had 6 or fewer contractions per hour, intact membranes, and <4 cm cervical dilation. Exclusion criteria included placental abruption or previa, fetal anomaly incompatible with life, or maternal medical contraindication to tocolysis. In order to have an 80% power to detect a 50% reduction in birth prior to 37 weeks, with an alpha of .05 and a beta of .2, 66 patients were required. Statistical comparisons were made using 2-sided Fisher’s Exact tests, Student t-tests, and Mann-Whitney tests.

      Results

      71 patients were randomized, 2 were excluded after randomization, and 1 was lost to follow up. 35 patient received placebo and 33 received nifedipine. There were no maternal demographic differences between groups. Results are shown in the table.
      Tabled 1Nifedipine vs. placebo outcomes
      NifedipinePlacebop-value
      Achieved 37 weeks13 (39%)13 (37%)1.00
      Delivery delay (days)31300.81
      Mean GA delivery35.035.20.82
      Delivery delay >48 hours33 (100%)33 (94%)0.49
       >1 week31 (94%)31 (89%)0.67
       >2 weeks28 (85%)27 (77%)0.54
       >3 weeks24 (73%)24 (69%)0.54
       >4 weeks22 (67)19 (54%)0.33
      BW (grams)245325310.69
      Composite neonatal morbidity10 (30%)7 (20%)0.41

      Conclusion

      Prolonged tocolysis following an episode of arrested preterm labor did not significantly prolong pregnancy or improve neonatal outcomes.