title: Early prenatal exposure to air pollution and its associations with birth defects in a state-wide birth cohort from North Carolina.
abstract: BACKGROUND
  Few studies have examined the potential relationship between air pollution and birth defects. The objective of this study was to investigate whether maternal exposure to particulate matter (PM2.5 ) and ozone (O3 ) during pregnancy is associated with birth defects among women living throughout North Carolina.
  
  
  METHODS
  Information on maternal and infant characteristics was obtained from North Carolina birth certificates and health service data (2003-2005) and linked with information on birth defects from the North Carolina Birth Defects Monitoring Program. The 24-hr PM2.5 and O3 concentrations were estimated using a hierarchical Bayesian model of air pollution generated by combining modeled air pollution predictions from the U.S. Environmental Protection Agency's Community Multi-Scale Air Quality model with air monitor data from the Environmental Protection Agency's Air Quality System. Maternal residence was geocoded and assigned pollutant concentrations averaged over weeks 3 to 8 of gestation. Binomial regression was performed and adjusted for potential confounders.
  
  
  RESULTS
  No association was observed between either PM2.5 or O3 concentrations and most birth defects. Positive effect estimates were observed between air pollution and microtia/anotia and lower limb deficiency defects, but the 95% confidence intervals were wide and included the null.
  
  
  CONCLUSIONS
  Overall, this study suggested a possible relationship between air pollution concentration during early pregnancy and certain birth defects (e.g., microtia/anotia, lower limb deficiency defects), although this study did not have the power to detect such an association. The risk for most birth defects does not appear to be affected by ambient air pollution.
authors.affiliation: National Center for Environmental Assessment (NCEA), U.S. Environmental Protection Agency (EPA), Research Triangle Park, North Carolina.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Vinikoor-Imler
authors.forename: J Allen
authors.initials: JA
authors.lastname: Davis
authors.forename: Robert E
authors.initials: RE
authors.lastname: Meyer
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Luben
mesh_terms: D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D001499:Bayes Theorem; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000453:epidemiology* / Q000209:etiology; D065817:Congenital Microtia; D004423:Ear / Q000002:abnormalities*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D062305:Geographic Mapping; D005865:Gestational Age; D006801:Humans; D007223:Infant; D038061:Lower Extremity Deformities, Congenital / Q000453:epidemiology* / Q000209:etiology; D018811:Maternal Exposure / Q000009:adverse effects*; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D010126:Ozone / Q000009:adverse effects*; D052638:Particulate Matter / Q000009:adverse effects*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012044:Regression Analysis
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D010126:Ozone
keywords: air pollution; birth defects; birth outcomes; ozone; particulate matter