title: Associations between maternal exposure to air pollution and traffic noise and newborn's size at birth: A cohort study.
abstract: Maternal exposure to air pollution and traffic noise has been suggested to impair fetal growth, but studies have reported inconsistent findings. Objective To investigate associations between residential air pollution and traffic noise during pregnancy and newborn's size at birth.
  
  
  
  From a national birth cohort we identified 75,166 live-born singletons born at term with information on the children's size at birth. Residential address history from conception until birth was collected and air pollution (NO2 and NOx) and road traffic noise was modeled at all addresses. Associations between exposures and indicators of newborn's size at birth: birth weight, placental weight and head and abdominal circumference were analyzed by linear and logistic regression, and adjusted for potential confounders.
  
  
  
  In mutually adjusted models we found a 10μg/m(3) higher time-weighted mean exposure to NO2 during pregnancy to be associated with a 0.35mm smaller head circumference (95% confidence interval (CI): 95% CI: -0.57; -0.12); a 0.50mm smaller abdominal circumference (95% CI: -0.80; -0.20) and a 5.02g higher placental weight (95% CI: 2.93; 7.11). No associations were found between air pollution and birth weight. Exposure to residential road traffic noise was weakly associated with reduced head circumference, whereas none of the other newborn's size indicators were associated with noise, neither before nor after adjustment for air pollution.
  
  
  
  This study indicates that air pollution may result in a small reduction in offspring's birth head and abdominal circumference, but not birth weight, whereas traffic noise seems not to affect newborn's size at birth.
authors.affiliation: Danish Cancer Society Research Centre, Copenhagen, Denmark. Electronic address: dorhjo@cancer.dk.
authors.forename: Dorrit
authors.initials: D
authors.lastname: Hjortebjerg
authors.affiliation: Section of Social Medicine, Department of Public Health, University of Copenhagen, Denmark.
authors.forename: Anne Marie Nybo
authors.initials: AM
authors.lastname: Andersen
authors.affiliation: Department of Environmental Science, Aarhus University, Roskilde, Denmark.
authors.forename: Matthias
authors.initials: M
authors.lastname: Ketzel
authors.affiliation: Danish Cancer Society Research Centre, Copenhagen, Denmark.
authors.forename: Marie
authors.initials: M
authors.lastname: Pedersen
authors.affiliation: Danish Cancer Society Research Centre, Copenhagen, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Raaschou-Nielsen
authors.affiliation: Danish Cancer Society Research Centre, Copenhagen, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Sørensen
mesh_terms: D000328:Adult; D000393:Air Pollutants; D000397:Air Pollution / Q000009:adverse effects*; D001724:Birth Weight; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development; D006798:Housing; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D009622:Noise; D009624:Noise, Transportation / Q000009:adverse effects*; D011247:Pregnancy; D055815:Young Adult
chemical_list: D000393:Air Pollutants
keywords: Air pollution; Birth weight; Cohort; Epidemiology; Fetal growth; Traffic noise