Objective: To clarify the relative efficacy of nifedipine and beta-agonists for tocolysis.
Data Sources: The literature was searched in the following databases: MEDLINE 1965–1998, Embase 1988–1998, Current Contents 1997–1998, and the Cochrane Database for 1998. We also sought unpublished trials and abstracts submitted to major international congresses. Search terms were: “tocolysis,” “nifedipine,” “calcium channel blocker,” “ritodrine,” “terbutaline,” and “salbutamol.”
Methods of Study Selection: Randomized controlled trials comparing tocolysis with nifedipine and beta-adrenergic agonists during preterm labor were reviewed. In cases with postrandomization exclusions, authors were contacted to obtain intent-to-treat results and to avoid analytical bias. We identified 11 published and two unpublished randomized trials.
Tabulation, Integration, and Results: Data were extracted by two reviewers and analyzed by a blinded biostatistician with RevMan 3.1 software from the Cochrane Collaboration. We analyzed nine relevant randomized controlled trials that included 679 patients. Meta-analysis showed that nifedipine was more effective than the beta-agonists in delaying delivery at least 48 hours [odds ratio (OR) 1.52, 95% confidence interval (CI) 1.03, 2.24], or over 34 weeks (OR 1.87, 95% CI 1.11, 3.15). The agents did not differ as to the incidence of deliveries after 37 weeks (OR 1.29, 95% CI 0.85, 1.96) or the neonatal mortality rate (OR 1.51, 95% CI 0.63, 3.65). Treatment with nifedipine was interrupted significantly less often because of side effects (OR 0.12, 95% CI 0.05, 0.29) and led to better neonatal outcomes (fewer infants with respiratory distress syndrome: OR 0.57, 95% CI 0.37, 0.89) or transferred to neonatal intensive care units (OR 0.65, 95% CI 0.43, 0.97).
Conclusion: With respect to neonatal outcome, nifedipine appears to be more effective than beta-agonists for tocolysis and should be considered for use as a first-line tocolytic agent.
Tocolysis with nifedipine gives better neonatal outcome than beta-agonists.
Department of Obstetrics and Gynecology, Hôpital Saint-Antoine, Paris, France; Department of Obstetrics and Gynecology, Free University Hospital, Amsterdam, The Netherlands; Epidemiological Research Unit on Women and Children's Health, INSERM U 149, Paris, France; and North Western Adelaide Health Service, University of Adelaide, Adelaide, South Australia.
Address reprint requests to: Bruno Carbonne, MD Department of Obstetrics and Gynecology, Hopital Saint Antoine, 184 rue du Faubourg Saint Antoine, 75012 Paris, France. E-mail: email@example.com
We thank J.A. Garcia-Velasco, J.E. Ferguson, E. Janky, C.A.M. Koks, and M. Kupferminc, who kindly provided additional data from their original study for this meta-analysis.
Received July 17, 2000. Received in revised form November 6, 2000. Accepted December 12, 2000.