title: Autism spectrum disorder and particulate matter air pollution before, during, and after pregnancy: a nested case-control analysis within the Nurses' Health Study II Cohort.
abstract: BACKGROUND
  Autism spectrum disorder (ASD) is a developmental disorder with increasing prevalence worldwide, yet has unclear etiology.
  
  
  OBJECTIVE
  We explored the association between maternal exposure to particulate matter (PM) air pollution and odds of ASD in her child.
  
  
  METHODS
  We conducted a nested case-control study of participants in the Nurses' Health Study II (NHS II), a prospective cohort of 116,430 U.S. female nurses recruited in 1989, followed by biennial mailed questionnaires. Subjects were NHS II participants' children born 1990-2002 with ASD (n = 245), and children without ASD (n = 1,522) randomly selected using frequency matching for birth years. Diagnosis of ASD was based on maternal report, which was validated against the Autism Diagnostic Interview-Revised in a subset. Monthly averages of PM with diameters ≤ 2.5 μm (PM2.5) and 2.5-10 μm (PM10-2.5) were predicted from a spatiotemporal model for the continental United States and linked to residential addresses.
  
  
  RESULTS
  PM2.5 exposure during pregnancy was associated with increased odds of ASD, with an adjusted odds ratio (OR) for ASD per interquartile range (IQR) higher PM2.5 (4.42 μg/m3) of 1.57 (95% CI: 1.22, 2.03) among women with the same address before and after pregnancy (160 cases, 986 controls). Associations with PM2.5 exposure 9 months before or after the pregnancy were weaker in independent models and null when all three time periods were included, whereas the association with the 9 months of pregnancy remained (OR = 1.63; 95% CI: 1.08, 2.47). The association between ASD and PM2.5 was stronger for exposure during the third trimester (OR = 1.42 per IQR increase in PM2.5; 95% CI: 1.09, 1.86) than during the first two trimesters (ORs = 1.06 and 1.00) when mutually adjusted. There was little association between PM10-2.5 and ASD.
  
  
  CONCLUSIONS
  Higher maternal exposure to PM2.5 during pregnancy, particularly the third trimester, was associated with greater odds of a child having ASD.
authors.affiliation: Department of Environmental Health, Department of Social and Behavioral Sciences, and Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.
authors.forename: Raanan
authors.initials: R
authors.lastname: Raz
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Roberts
authors.forename: Kristen
authors.initials: K
authors.lastname: Lyall
authors.forename: Jaime E
authors.initials: JE
authors.lastname: Hart
authors.forename: Allan C
authors.initials: AC
authors.lastname: Just
authors.forename: Francine
authors.initials: F
authors.lastname: Laden
authors.forename: Marc G
authors.initials: MG
authors.lastname: Weisskopf
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000453:epidemiology*; D002675:Child, Preschool; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D008297:Male; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D052638:Particulate Matter / Q000032:analysis*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter