title: The association of air pollution with birthweight and gestational age: evidence from Hong Kong's 'Children of 1997' birth cohort.
abstract: Previous studies from Western settings have found inconsistent associations of air pollutants with birth outcomes, which are open to residual confounding by socioeconomic position (SEP). We assessed this association in the economically developed non-Western setting of Hong Kong, with high levels of air pollution but little social patterning of these outcomes.
  
  
  
  We obtained PM10, SO2, NO and NO2 from monitoring stations, and assessed their associations with birthweight and gestational age in a large population-representative birth cohort 'Children of 1997', using partial least-square regression to account for the colinearity between pollutants.
  
  
  
  PM10 (per 5.7 µg/m3 higher) and NO2 (per 10.9 µg/m3 higher) were associated with birthweight lower by 47.0 g (95% confidence interval (CI) 36.2-56.3) and 16.9 g (95% CI 10.8-22.6), respectively; and were associated with gestational age shorter by 2.1 days (95% CI 1.7-2.4) and 0.7 days (95% CI 0.5-0.8), respectively.
  
  
  
  Given minimal confounding by SEP in our setting, these findings provide unequivocal evidence of adverse effects of PM10 and NO2 exposure during pregnancy on birthweight and gestational age. Physiological mechanisms need to be better understood to support effective public health action globally.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China.
authors.forename: Jian V
authors.initials: JV
authors.lastname: Huang
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China.
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China.|City University of New York, Graduate School of Public Health and Health Policy, New York, NY, USA.
authors.forename: C Mary
authors.initials: CM
authors.lastname: Schooling
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D001724:Birth Weight / Q000187:drug effects*; D005260:Female; D005865:Gestational Age; D006723:Hong Kong; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009569:Nitric Oxide / Q000009:adverse effects; D009585:Nitrogen Dioxide / Q000009:adverse effects; D052638:Particulate Matter; D011247:Pregnancy; D011256:Pregnancy Outcome; D055815:Young Adult
chemical_list: D052638:Particulate Matter; D009569:Nitric Oxide; D009585:Nitrogen Dioxide
keywords: air pollution, environment, pregnancy, birth outcomes and
                      childbirth disorders