title: The impact of smoke-free legislation on educational differences in birth outcomes.
abstract: BACKGROUND
  Smoke-free legislation may have positive effects on birth outcomes. Given that smoking and secondhand smoke during pregnancy vary with socioeconomic position, legislation may have greater effects in some socioeconomic groups. For this study, we evaluated the impact of a 2006 ban on smoking in public places in the Canadian province of Quebec on preterm birth, small-for-gestational-age birth and birth weight, and on educational differences in these birth outcomes.
  
  
  METHODS
  We analysed data on singleton births in Quebec between 2003 and 2010. Logistic regression was used to model the association of smoke-free legislation with preterm birth (<37 weeks), very preterm birth (<34 weeks), small-for-gestational-age birth (<10th centile for gestational age and sex), low birth weight (<2500 g) and mean birth weight, adjusting for secular trends before and after legislation. Interaction terms were included to assess differential effects by level of maternal education.
  
  
  RESULTS
  Smoke-free legislation was associated with average reductions of 3.1 preterm births (95% CI 0.1 to 6.0), 2.3 very preterm births (95% CI 0.9 to 3.7), 5.9 small-for-gestational-age births (95% CI 2.6 to 9.3) and 1.0 low birthweight infants (95% CI 0.4 to 1.6) per 1000 live births, as well as a 17.1 g increase in mean birth weight (95% CI 10.7 to 23.6). Legislation was associated with improved birth outcomes in all categories of maternal education.
  
  
  CONCLUSIONS
  Smoke-free legislation in Quebec was associated with reductions in preterm and small-for-gestational-age births, and an increase in birth weight. There was no compelling evidence that legislation impacted educational gradients in birth outcomes.
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University Faculty of Medicine, Montreal, Quebec, Canada Institute for Health and Social Policy, McGill University, Montreal, Quebec, Canada.
authors.forename: Britt
authors.initials: B
authors.lastname: McKinnon
authors.affiliation: Institut national de santé publique du Québec, Montreal, Quebec, Canada University of Montreal Hospital Research Centre, Montreal, Quebec, Canada.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Auger
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University Faculty of Medicine, Montreal, Quebec, Canada Institute for Health and Social Policy, McGill University, Montreal, Quebec, Canada.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Kaufman
mesh_terms: D001719:Birth Certificates; D001724:Birth Weight; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007859:Learning Disabilities / Q000453:epidemiology; D016015:Logistic Models; D009035:Mothers / Q000193:education*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology; D015995:Prevalence; D011633:Public Facilities / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D011792:Quebec / Q000453:epidemiology; D012907:Smoking / Q000009:adverse effects / Q000331:legislation & jurisprudence*; D000074606:Smoking Prevention; D012959:Socioeconomic Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects / Q000331:legislation & jurisprudence* / Q000517:prevention & control
chemical_list: D014028:Tobacco Smoke Pollution
keywords: Health inequalities; PERINATAL EPIDEMIOLOGY; PUBLIC HEALTH POLICY; SMOKING