title: Nifedipine as a uterine relaxant for external cephalic version: a randomized controlled trial.
abstract: OBJECTIVE
  To estimate the effectiveness of nifedipine as a uterine relaxant during external cephalic version to correct breech presentation.
  
  
  METHODS
  In this randomized, double-blind, placebo-controlled trial, women with a singleton fetus in breech presentation and a gestational age of 36 weeks or more were eligible for enrollment. Participating women received two doses of either nifedipine 10 mg or placebo, 30 and 15 minutes before the external cephalic version attempt. The primary outcome was a cephalic-presenting fetus immediately after the procedure. Secondary outcome measures were cephalic presentation at delivery, mode of delivery, and adverse events. A sample size of 292 was calculated to provide 80% power to detect a 17% improvement of the external cephalic version success rate, assuming a placebo group rate of 40% and alpha of .05.
  
  
  RESULTS
  Outcome data for 310 of 320 randomly assigned participants revealed no significant difference in external cephalic version success rates between treatment (42%) and control group (37%) (relative risk 1.1, 95%; 95% confidence interval 0.85-1.5). The cesarean delivery rate was 51% in the treatment group and 46% in the control group (relative risk 1.1, 95% confidence interval 0.88-1.4).
  
  
  CONCLUSIONS
  Nifedipine did not significantly improve the success of external cephalic version. Future use of nifedipine to improve the outcome of external cephalic version should be limited to large clinical trials.
authors.affiliation: Departments of Obstetrics and Gynecology, Academic Medical Centre, Amsterdam; Medical Centre Alkmaar, Alkmaar, the Netherlands. mkok@amc.uva.nl
authors.forename: Marjolein
authors.initials: M
authors.lastname: Kok
authors.forename: Joke M
authors.initials: JM
authors.lastname: Bais
authors.forename: Jan M
authors.initials: JM
authors.lastname: van Lith
authors.forename: Dimitri M
authors.initials: DM
authors.lastname: Papatsonis
authors.forename: Gunilla
authors.initials: G
authors.lastname: Kleiverda
authors.forename: Dahrs
authors.initials: D
authors.lastname: Hanny
authors.forename: Johannes P
authors.initials: JP
authors.lastname: Doornbos
authors.forename: Ben W
authors.initials: BW
authors.lastname: Mol
authors.forename: Joris A
authors.initials: JA
authors.lastname: van der Post
mesh_terms: D000328:Adult; D001946:Breech Presentation / Q000601:surgery*; D002585:Cesarean Section / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D009543:Nifedipine / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D011247:Pregnancy; D015149:Tocolytic Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D014599:Uterus / Q000187:drug effects*; D014710:Version, Fetal / Q000379:methods
chemical_list: D015149:Tocolytic Agents; D009543:Nifedipine