title: Educational inequalities in perinatal outcomes: the mediating effect of smoking and environmental tobacco exposure.
abstract: OBJECTIVE
  Socioeconomic status (SES) is adversely associated with perinatal outcomes. This association is likely to be mediated by tobacco exposure. However, previous studies were limited to single perinatal outcomes and devoted no attention to environmental tobacco exposure. Therefore, this study aimed firstly to explain the role of maternal smoking in the association between maternal education and preterm birth (PTB), low birth weight (LBW) and small for gestational age (SGA), and secondly to explain whether environmental tobacco smoke mediates these associations further.
  
  
  METHODS
  This study was nested in a population-based cohort study in the Netherlands, the Amsterdam Born Children and their Development (ABCD) study. Analyses were done in a sample of 3821 pregnant women of Dutch origin, using logistic regression analysis.
  
  
  RESULTS
  Least educated women, who were more often smoking and exposed to environmental tobacco smoke, had a significantly higher risk of PTB (OR 1.95 [95% CI: 1.19-3.20]), LBW (OR 2.41 [95% CI: 1.36-4.27]) and SGA (OR 1.90 [95% CI 1.32-2.74]) than highly educated women. The mediating effect of smoking in the least educated women was 43% for PTB, 55% for LBW and 66% for SGA. Environmental tobacco smoke did not explain these associations further. After adjustment for maternal smoking, the association between lower maternal education and pregnancy outcomes was no longer significant.
  
  
  CONCLUSIONS
  Smoking explains to a considerable extent the association between lower maternal education and adverse perinatal outcomes. Therefore, tobacco-interventions in lower educated women should be primarily focussed on maternal smoking to reduce PTB, LBW, and SGA. Additional attention to environmental tobacco exposure does not seem to reduce educational inequalities in perinatal outcomes.
authors.affiliation: Department of Pediatrics, VU University Medical Center, Amsterdam, The Netherlands. g.vandenberg@vumc.nl
authors.forename: Gerrit
authors.initials: G
authors.lastname: van den Berg
authors.forename: Manon
authors.initials: M
authors.lastname: van Eijsden
authors.forename: Tanja G M
authors.initials: TG
authors.lastname: Vrijkotte
authors.forename: Reinoud J B J
authors.initials: RJ
authors.lastname: Gemke
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006266:Health Education; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D009426:Netherlands / Q000453:epidemiology; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution