Systematic review and meta-analysis of randomized controlled trials of atosiban versus nifedipine for inhibition of preterm labor

Background Two tocolytic drugs-atosiban and nifedipine-are currently used for first-line treatment of preterm labor (PTL). Objective To compare the efficacy and safety of atosiban with nifedipine for PTL treatment. Search strategy In May 2017, we searched PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Clinical Trials with search terms including "nifedipine", "atosiban", and "preterm labor". Selection criteria Randomized controlled trials of women with PTL. Data collection and analysis Data were extracted for study design, patient characteristics, risk of bias domains, and study outcomes. A random-effects model was used to generate pooled risk ratios (RRs) and 95% confidence intervals (CIs). Results We included seven studies that enrolled 992 patients. There was no significant difference between atosiban and nifedipine for pregnancy prolongation of 48 hours or more regarding efficacy (RR 1.06, 95% CI 0.92-1.22; P=0.440) or effectiveness (0.93, 0.84-1.03; P=0.177). Pregnancy prolongation for 7 days or more also did not differ between groups for efficacy (RR 1.04, 95% CI 0.89-1.21; P=0.656) or effectiveness (0.91, 0.79-1.05; P=0.177). Atosiban-however-was associated with fewer maternal side-effects than nifedipine. Conclusion Atosiban resulted in fewer maternal side-effects than nifedipine, with no difference in pregnancy prolongation.