title: Ambient Air Pollution and Newborn Size and Adiposity at Birth: Differences by Maternal Ethnicity (the Born in Bradford Study Cohort).
abstract: BACKGROUND
  Exposure to ambient air pollution has been associated with reduced size of newborns; however, the modifying effect of maternal ethnicity remains little explored among South Asians.
  
  
  OBJECTIVE
  We investigated ethnic differences in the association between ambient air pollution and newborn's size.
  
  
  METHODS
  Pregnant women were recruited between 2007 and 2010 for the Born in Bradford cohort study, in England. Exposures to particulate matter (≤ 10 μm, PM10; ≤ 2.5 μm, PM2.5), PM2.5 absorbance, and nitrogen oxides (NOx, NO2) were estimated using land-use regressions models. Using multivariate linear regression models, we evaluated effect modification by maternal ethnicity ("white British" or "Pakistani origin," self-reported) on the associations of air pollution and birth weight, head circumference, and triceps and subscapular skinfold thickness.
  
  
  RESULTS
  A 5-μg/m3 increase in mean third trimester PM2.5 was associated with significantly lower birth weight and smaller head circumference in children of white British mothers (-43 g; 95% CI: -76, -10 and -0.28 cm; 95% CI: -0.39, -0.17, respectively), but not in children of Pakistani origin (9 g; 95% CI: -17, 35 and -0.08 cm; 95% CI: -0.17, 0.01, respectively) (p(int) = 0.03 and < 0.001). In contrast, PM2.5 was associated with significantly larger triceps and subscapular skinfold thicknesses in children of Pakistani origin (0.17 mm; 95% CI: 0.08, 0.25 and 0.21 mm; 95% CI: 0.12, 0.29, respectively), but not in white British children (-0.02 mm; 95% CI: -0.14, 0.01 and 0.06 mm; 95% CI: -0.06, 0.18, respectively) (p(int) = 0.06 and 0.11). Patterns of associations for PM10 and PM2.5 absorbance according to ethnicity were similar to those for PM2.5, but associations of the outcomes with NO2 and NOx were mostly nonsignificant in both ethnic groups.
  
  
  CONCLUSIONS
  Our results suggest that associations of ambient PM exposures with newborn size and adiposity differ between white British and Pakistani origin infants.
  
  
  BACKGROUND
  Schembari A, de Hoogh K, Pedersen M, Dadvand P, Martinez D, Hoek G, Petherick ES, Wright J, Nieuwenhuijsen MJ. 2015. Ambient air pollution and newborn size and adiposity at birth: differences by maternal ethnicity (the Born in Bradford study cohort). Environ Health Perspect 123:1208-1215; http://dx.doi.org/10.1289/ehp.1408675.
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Schembari
authors.forename: Kees
authors.initials: K
authors.lastname: de Hoogh
authors.forename: Marie
authors.initials: M
authors.lastname: Pedersen
authors.forename: Payam
authors.initials: P
authors.lastname: Dadvand
authors.forename: David
authors.initials: D
authors.lastname: Martinez
authors.forename: Gerard
authors.initials: G
authors.lastname: Hoek
authors.forename: Emily S
authors.initials: ES
authors.lastname: Petherick
authors.forename: John
authors.initials: J
authors.lastname: Wright
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
mesh_terms: D050154:Adiposity; D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D001724:Birth Weight / Q000502:physiology*; D002508:Cephalometry; D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects; D005006:Ethnicity; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D009589:Nitrogen Oxides / Q000009:adverse effects*; D010154:Pakistan / Q000208:ethnology; D052638:Particulate Matter / Q000009:adverse effects*; D011247:Pregnancy; D012885:Skinfold Thickness; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D052638:Particulate Matter