title: Prenatal Particulate Air Pollution and Asthma Onset in Urban Children. Identifying Sensitive Windows and Sex Differences.
abstract: BACKGROUND
  The influence of particulate air pollution on respiratory health starts in utero. Fetal lung growth and structural development occurs in stages; thus, effects on postnatal respiratory disorders may differ based on timing of exposure.
  
  
  OBJECTIVE
  We implemented an innovative method to identify sensitive windows for effects of prenatal exposure to particulate matter with a diameter less than or equal to 2.5 μm (PM2.5) on children's asthma development in an urban pregnancy cohort.
  
  
  METHODS
  Analyses included 736 full-term (≥37 wk) children. Each mother's daily PM2.5 exposure was estimated over gestation using a validated satellite-based spatiotemporal resolved model. Using distributed lag models, we examined associations between weekly averaged PM2.5 levels over pregnancy and physician-diagnosed asthma in children by age 6 years. Effect modification by sex was also examined.
  
  
  RESULTS
  Most mothers were ethnic minorities (54% Hispanic, 30% black), had 12 or fewer years of education (66%), and did not smoke in pregnancy (80%). In the sample as a whole, distributed lag models adjusting for child age, sex, and maternal factors (education, race and ethnicity, smoking, stress, atopy, prepregnancy obesity) showed that increased PM2.5 exposure levels at 16-25 weeks gestation were significantly associated with early childhood asthma development. An interaction between PM2.5 and sex was significant (P = 0.01) with sex-stratified analyses showing that the association exists only for boys.
  
  
  CONCLUSIONS
  Higher prenatal PM2.5 exposure at midgestation was associated with asthma development by age 6 years in boys. Methods to better characterize vulnerable windows may provide insight into underlying mechanisms.
authors.affiliation: 1 Department of Preventive Medicine.
authors.forename: Hsiao-Hsien Leon
authors.initials: HH
authors.lastname: Hsu
authors.affiliation: 2 Kravis Children's Hospital, Department of Pediatrics.
authors.forename: Yueh-Hsiu Mathilda
authors.initials: YH
authors.lastname: Chiu
authors.affiliation: 3 Department of Biostatistics.|4 Department of Environmental Health, and.
authors.forename: Brent A
authors.initials: BA
authors.lastname: Coull
authors.affiliation: 4 Department of Environmental Health, and.|5 Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beersheba, Israel.
authors.forename: Itai
authors.initials: I
authors.lastname: Kloog
authors.affiliation: 4 Department of Environmental Health, and.|6 Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; and.
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.affiliation: 7 Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, and.
authors.forename: Alison
authors.initials: A
authors.lastname: Lee
authors.affiliation: 1 Department of Preventive Medicine.|8 The Mindich Child Health & Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Robert O
authors.initials: RO
authors.lastname: Wright
authors.affiliation: 2 Kravis Children's Hospital, Department of Pediatrics.|8 The Mindich Child Health & Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Rosalind J
authors.initials: RJ
authors.lastname: Wright
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000706:statistics & numerical data*; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D052638:Particulate Matter / Q000032:analysis*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D012307:Risk Factors; D012737:Sex Factors; D014481:United States / Q000453:epidemiology; D014504:Urban Health / Q000706:statistics & numerical data*; D014505:Urban Population / Q000706:statistics & numerical data
chemical_list: D052638:Particulate Matter
keywords: asthma; fine particulate matter; prenatal exposure; sensitive windows; sex difference