Objective: To evaluate whether tocolysis with nifedipine can be omitted in women with symptoms of preterm labor, a shortened cervix, and negative fetal fibronectin test.
Study design: A randomized noninferiority trial was performed in all Dutch perinatal centers. Women with symptoms of preterm labor between 24 and 34 weeks, intact membranes, cervical length between 10 and 30 mm, and negative fibronectin test were randomly allocated to nifedipine (80 mg/day) or placebo. The primary outcome was delivery within 7 days. Secondary outcomes were severe neonatal morbidity and mortality. We also followed all eligible nonrandomized women.
Results: We allocated 37 women to nifedipine and 36 women to placebo. In the nifedipine group, three women (8.1%) delivered within 7 days, compared with one woman (2.8%) in the placebo group (difference -5.3%; one-sided 95% confidence limit 4.5%). Median gestational age at delivery were respectively 37 + 0 (interquartile range [IQR] 34 + 6 to 38 + 5) and 38 + 2 (IQR 37 + 0 to 39 + 6) weeks (p = 0.008). In the nifedipine group, three pregnancies (8.1%) had a poor outcome; there were no poor outcomes in the placebo group. We observed similar trends in eligible nonrandomized women.
Conclusion: In symptomatic women with preterm labor, a shortened cervix, and negative fibronectin test, placebo treatment is not inferior to tocolysis with nifedipine.
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