title: Caffeine consumption during pregnancy and risk of preterm birth: a meta-analysis.
abstract: BACKGROUND
  The effect of caffeine intake during pregnancy on the risk of preterm delivery has been studied for the past 3 decades with inconsistent results.
  
  
  OBJECTIVE
  We performed a meta-analysis examining the association between caffeine consumption during pregnancy and risk of preterm birth.
  
  
  METHODS
  We searched MEDLINE and EMBASE articles published between 1966 and July 2010, cross-referenced reference lists of the retrieved articles, and identified 15 cohort and 7 case-control studies that met inclusion criteria for this meta-analysis.
  
  
  RESULTS
  The combined odds ratios (ORs) obtained by using fixed-effects models for cohort studies were 1.11 (95% CI: 0.96, 1.28), 1.10 (95% CI: 1.01, 1.19), and 1.08 (95% CI: 0.93, 1.27) for risk of preterm birth comparing the highest with the lowest level of caffeine intake (or no intake) (mg/d) during the first, second, and third trimesters, respectively. Results for the case-control studies yielded no associations for the first (OR: 1.07; 95% CI: 0.84, 1.37), second (OR: 1.17; 95% CI: 0.94, 1.45), or third (OR: 0.94; 95% CI: 0.79, 1.12) trimesters. No overall heterogeneity was found by region, publication decade, exposure and outcome assessment, caffeine sources, or adjustment for confounding, which was largely driven by individual studies.
  
  
  CONCLUSIONS
  In this meta-analysis, we observed no important association between caffeine intake during pregnancy and the risk of preterm birth for cohort and case-control studies.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA. emaslova@hsph.harvard.edu
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Maslova
authors.forename: Sayanti
authors.initials: S
authors.lastname: Bhattacharya
authors.forename: Shih-Wen
authors.initials: SW
authors.lastname: Lin
authors.forename: Karin B
authors.initials: KB
authors.lastname: Michels
mesh_terms: D002110:Caffeine / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000139:chemically induced; D016017:Odds Ratio; D028321:Plant Preparations / Q000009:adverse effects*; D011247:Pregnancy; D047928:Premature Birth / Q000209:etiology*; D012307:Risk Factors
chemical_list: D028321:Plant Preparations; D002110:Caffeine