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. PROSPERO registration: CRD42018090223.