title: Comparison of black-white disparities in preterm birth between Canada and the United States.
abstract: BACKGROUND
  A higher risk of preterm birth among black women than among white women is well established in the United States. We compared differences in preterm birth between non-Hispanic black and white women in Canada and the US, hypothesizing that disparities would be less extreme in Canada given the different historical experiences of black populations and Canada's universal health care system.
  
  
  METHODS
  Using data on singleton live births in Canada and the US for 2004-2006, we estimated crude and adjusted risk ratios and risk differences in preterm birth (< 37 wk) and very preterm birth (< 32 wk) among non-Hispanic black versus non-Hispanic white women in each country. Adjusted models for the US were standardized to the covariate distribution of the Canadian cohort.
  
  
  RESULTS
  In Canada, 8.9% and 5.9% of infants born to black and white mothers, respectively, were preterm; the corresponding figures in the US were 12.7% and 8.0%. Crude risk ratios for preterm birth among black women relative to white women were 1.49 (95% confidence interval [CI] 1.32 to 1.66) in Canada and 1.57 (95% CI 1.56 to 1.58) in the US (p value for heterogeneity [pH] = 0.3). The crude risk differences for preterm birth were 2.94 (95% CI 1.91 to 3.96) in Canada and 4.63 (95% CI 4.56 to 4.70) in the US (pH = 0.003). Adjusted risk ratios for preterm birth (pH = 0.1) were slightly higher in Canada than in the US, whereas adjusted risk differences were similar in both countries. Similar patterns were observed for racial disparities in very preterm birth.
  
  
  CONCLUSIONS
  Relative disparities in preterm birth and very preterm birth between non-Hispanic black and white women were similar in magnitude in Canada and the US. Absolute disparities were smaller in Canada, which reflects a lower overall risk of preterm birth in Canada than in the US in both black and white populations.
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health (McKinnon, Yang, Kramer, Kaufman), McGill University Faculty of Medicine, Montréal, Que.; Institute for Health and Social Policy (McKinnon, Kaufman), McGill University, Montréal, Que.; Department of Pediatrics (Kramer), McGill University Faculty of Medicine, Montréal, Que.; Health Analysis Division (Bushnik), Statistics Canada, Ottawa, Ont.; AboutKidsHealth (Sheppard), The Hospital for Sick Children, Toronto, Ont.; Dalla Lana School of Public Health (Sheppard), University of Toronto, Toronto, Ont. britt.mckinnon@mcgill.ca.
authors.forename: Britt
authors.initials: B
authors.lastname: McKinnon
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health (McKinnon, Yang, Kramer, Kaufman), McGill University Faculty of Medicine, Montréal, Que.; Institute for Health and Social Policy (McKinnon, Kaufman), McGill University, Montréal, Que.; Department of Pediatrics (Kramer), McGill University Faculty of Medicine, Montréal, Que.; Health Analysis Division (Bushnik), Statistics Canada, Ottawa, Ont.; AboutKidsHealth (Sheppard), The Hospital for Sick Children, Toronto, Ont.; Dalla Lana School of Public Health (Sheppard), University of Toronto, Toronto, Ont.
authors.forename: Seungmi
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health (McKinnon, Yang, Kramer, Kaufman), McGill University Faculty of Medicine, Montréal, Que.; Institute for Health and Social Policy (McKinnon, Kaufman), McGill University, Montréal, Que.; Department of Pediatrics (Kramer), McGill University Faculty of Medicine, Montréal, Que.; Health Analysis Division (Bushnik), Statistics Canada, Ottawa, Ont.; AboutKidsHealth (Sheppard), The Hospital for Sick Children, Toronto, Ont.; Dalla Lana School of Public Health (Sheppard), University of Toronto, Toronto, Ont.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kramer
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health (McKinnon, Yang, Kramer, Kaufman), McGill University Faculty of Medicine, Montréal, Que.; Institute for Health and Social Policy (McKinnon, Kaufman), McGill University, Montréal, Que.; Department of Pediatrics (Kramer), McGill University Faculty of Medicine, Montréal, Que.; Health Analysis Division (Bushnik), Statistics Canada, Ottawa, Ont.; AboutKidsHealth (Sheppard), The Hospital for Sick Children, Toronto, Ont.; Dalla Lana School of Public Health (Sheppard), University of Toronto, Toronto, Ont.
authors.forename: Tracey
authors.initials: T
authors.lastname: Bushnik
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health (McKinnon, Yang, Kramer, Kaufman), McGill University Faculty of Medicine, Montréal, Que.; Institute for Health and Social Policy (McKinnon, Kaufman), McGill University, Montréal, Que.; Department of Pediatrics (Kramer), McGill University Faculty of Medicine, Montréal, Que.; Health Analysis Division (Bushnik), Statistics Canada, Ottawa, Ont.; AboutKidsHealth (Sheppard), The Hospital for Sick Children, Toronto, Ont.; Dalla Lana School of Public Health (Sheppard), University of Toronto, Toronto, Ont.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Sheppard
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health (McKinnon, Yang, Kramer, Kaufman), McGill University Faculty of Medicine, Montréal, Que.; Institute for Health and Social Policy (McKinnon, Kaufman), McGill University, Montréal, Que.; Department of Pediatrics (Kramer), McGill University Faculty of Medicine, Montréal, Que.; Health Analysis Division (Bushnik), Statistics Canada, Ottawa, Ont.; AboutKidsHealth (Sheppard), The Hospital for Sick Children, Toronto, Ont.; Dalla Lana School of Public Health (Sheppard), University of Toronto, Toronto, Ont.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Kaufman
mesh_terms: D000328:Adult; D044383:Black People; D002170:Canada / Q000453:epidemiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D016017:Odds Ratio; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D044465:White People; D055815:Young Adult; D001741:Black or African American