title: Maternal exposure to criteria air pollutants and congenital heart defects in offspring: results from the national birth defects prevention study.
abstract: BACKGROUND
  Epidemiologic literature suggests that exposure to air pollutants is associated with fetal development.
  
  
  OBJECTIVE
  We investigated maternal exposures to air pollutants during weeks 2-8 of pregnancy and their associations with congenital heart defects.
  
  
  METHODS
  Mothers from the National Birth Defects Prevention Study, a nine-state case-control study, were assigned 1-week and 7-week averages of daily maximum concentrations of carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide and 24-hr measurements of fine and coarse particulate matter using the closest air monitor within 50 km to their residence during early pregnancy. Depending on the pollutant, a maximum of 4,632 live-birth controls and 3,328 live-birth, fetal-death, or electively terminated cases had exposure data. Hierarchical regression models, adjusted for maternal demographics and tobacco and alcohol use, were constructed. Principal component analysis was used to assess these relationships in a multipollutant context.
  
  
  RESULTS
  Positive associations were observed between exposure to nitrogen dioxide and coarctation of the aorta and pulmonary valve stenosis. Exposure to fine particulate matter was positively associated with hypoplastic left heart syndrome but inversely associated with atrial septal defects. Examining individual exposure-weeks suggested associations between pollutants and defects that were not observed using the 7-week average. Associations between left ventricular outflow tract obstructions and nitrogen dioxide and between hypoplastic left heart syndrome and particulate matter were supported by findings from the multipollutant analyses, although estimates were attenuated at the highest exposure levels.
  
  
  CONCLUSIONS
  Using daily maximum pollutant levels and exploring individual exposure-weeks revealed some positive associations between certain pollutants and defects and suggested potential windows of susceptibility during pregnancy.
authors.affiliation: Department of Epidemiology, UNC Gillings School of Global Public Health, Chapel Hill, North Carolina, USA.
authors.forename: Jeanette A
authors.initials: JA
authors.lastname: Stingone
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Luben
authors.forename: Julie L
authors.initials: JL
authors.lastname: Daniels
authors.forename: Montserrat
authors.initials: M
authors.lastname: Fuentes
authors.forename: David B
authors.initials: DB
authors.lastname: Richardson
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Aylsworth
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Marlene
authors.initials: M
authors.lastname: Anderka
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Botto
authors.forename: Adolfo
authors.initials: A
authors.lastname: Correa
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Gilboa
authors.forename: Peter H
authors.initials: PH
authors.lastname: Langlois
authors.forename: Bridget
authors.initials: B
authors.lastname: Mosley
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
authors.forename: Csaba
authors.initials: C
authors.lastname: Siffel
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
mesh_terms: D000393:Air Pollutants; D005260:Female; D006330:Heart Defects, Congenital / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D018811:Maternal Exposure / Q000009:adverse effects*; D009585:Nitrogen Dioxide / Q000633:toxicity; D010126:Ozone / Q000633:toxicity; D052638:Particulate Matter / Q000633:toxicity*; D011247:Pregnancy; D013458:Sulfur Dioxide / Q000633:toxicity
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D009585:Nitrogen Dioxide
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