title: Calcium channel blockers for inhibiting preterm labour.
abstract: BACKGROUND
  Preterm birth is a major contributor to perinatal mortality and morbidity and affects approximately six to seven per cent of births in developed countries. Tocolytics are drugs used to suppress uterine contractions. The most widely tested tocolytics are betamimetics. Although they have been shown to delay delivery, betamimetics have not been shown to improve perinatal outcome, and they have a high frequency of unpleasant and even fatal maternal side effects. There is growing interest in calcium channel blockers as a potentially effective and well tolerated form of tocolysis.
  
  
  OBJECTIVE
  To assess the effects on maternal, fetal and neonatal outcomes of calcium channel blockers, administered as a tocolytic agent, to women in preterm labour.
  
  
  METHODS
  We searched the Cochrane Pregnancy and Childbirth Group's specialised register of controlled trials, the Cochrane Controlled Trials Register (February 2002), MEDLINE, EMBASE, and Current Contents. We also contacted recognised experts and cross referenced relevant material.
  
  
  METHODS
  All published and unpublished randomised trials in which calcium channel blockers were used for tocolysis for women in labour between 20 and 36 weeks gestation.
  
  
  METHODS
  Standard methods of the Cochrane Collaboration and the Cochrane Pregnancy and Childbirth Group were used. Evaluation of methodological quality and trial data extraction were undertaken independently by three authors. Additional information was sought to enable assessment of methodology and conduct of intention-to-treat analyses. Meta-analysis was conducted assessing the effects of calcium channel blockers compared with any other tocolytic agent. Results are presented using relative risk for categorical data and weighted mean difference for continuous data.
  
  
  RESULTS
  Eleven randomised controlled trials involving 870 women were included. When compared with any other tocolytic agent (mainly betamimetics), calcium channel blockers reduced the number of women giving birth within 48 hours (relative risk (RR) 0.73; 95% confidence interval (CI) 0.54, 0.98) and within seven days (RR 0.76; 95% CI 0.59, 0.99). Calcium channel blockers also reduced the requirement for women to have treatment ceased for adverse drug reaction (RR 0.15; 95% CI 0.06, 0.43), the frequency of neonatal respiratory distress syndrome (RR 0.64; 95% CI 0.45, 0.91) and neonatal jaundice (RR 0.73; 95% CI 0.57, 0.93).
  
  
  CONCLUSIONS
  When tocolysis is indicated for women in preterm labour, calcium channel blockers are preferable to betamimetic agents. Further research should address the effects of different dosage regimens and formulations of nifedipine on maternal and neonatal outcomes.
authors.affiliation: Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Victoria, Australia, 3053. jfking@unimelb.edu.au
authors.forename: J F
authors.initials: JF
authors.lastname: King
authors.forename: V J
authors.initials: VJ
authors.lastname: Flenady
authors.forename: D N
authors.initials: DN
authors.lastname: Papatsonis
authors.forename: G A
authors.initials: GA
authors.lastname: Dekker
authors.forename: B
authors.initials: B
authors.lastname: Carbonne
mesh_terms: D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic; D015149:Tocolytic Agents / Q000627:therapeutic use*
chemical_list: D002121:Calcium Channel Blockers; D015149:Tocolytic Agents