title: Multiple courses of antenatal corticosteroids: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To assess the effects of multiple courses of antenatal corticosteroids on perinatal and neonatal death and neonatal, infant, and maternal disease.
  
  
  METHODS
  MEDLINE and Embase were searched for human studies published in English. Studies that compared multiple courses of antenatal corticosteroids versus a single course were included if they were published in full and were controlled for gestational age at birth. Meta-analyses (odds ratio and 95% confidence interval) were undertaken when possible.
  
  
  RESULTS
  Eight observational studies were included. Selection bias was present in all studies. Multiple courses of antenatal corticosteroids were associated with a decreased risk of respiratory distress syndrome (odds ratio, 0.79; 95% confidence interval, 0.64 to 0.98) and patent ductus arteriosus (odds ratio, 0.56; 95% confidence interval, 0.35 to 0.90) and were associated with an increased risk of endometritis (odds ratio, 3.42; 95% confidence interval, 1.92 to 6.11). There was no significant effect on other neonatal and maternal outcomes.
  
  
  CONCLUSIONS
  It is not possible to establish the true effects of multiple courses of antenatal corticosteroids by a review of the results of observational studies because of the effect of confounding variables. Randomized controlled trials are needed to address this important issue.
authors.affiliation: Institute of Medical Sciences, Center for Research in Women's Health, University of Toronto, Ontario, Canada. fariba.aghajafari@utoronto.ca
authors.forename: F
authors.initials: F
authors.lastname: Aghajafari
authors.forename: K
authors.initials: K
authors.lastname: Murphy
authors.forename: A
authors.initials: A
authors.lastname: Willan
authors.forename: A
authors.initials: A
authors.lastname: Ohlsson
authors.forename: K
authors.initials: K
authors.lastname: Amankwah
authors.forename: S
authors.initials: S
authors.lastname: Matthews
authors.forename: M
authors.initials: M
authors.lastname: Hannah
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage* / Q000009:adverse effects*; D004716:Endometritis / Q000139:chemically induced*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016017:Odds Ratio; D011247:Pregnancy; D011295:Prenatal Care; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*
chemical_list: D000305:Adrenal Cortex Hormones