title: Particulate air pollution, fetal growth and gestational length: The influence of residential mobility in pregnancy.
abstract: BACKGROUND
  It remains unclear as to whether neglecting residential mobility during pregnancy introduces bias in studies investigating air pollution and adverse perinatal outcomes, as most studies assess exposure based on residence at birth. The aim of this study was to ascertain whether such bias can be observed in a study on the effects of PM10 on risk of preterm birth and fetal growth restriction.
  
  
  METHODS
  This was a retrospective study using four pregnancy cohorts of women recruited in Connecticut, USA (N=10,025). We ascertained associations with PM10 exposure calculated using first recorded maternal address, last recorded address, and full address histories. We used a discrete time-to-event model for preterm birth, and logistic regression to investigate associations with small for gestational age (SGA) and term low birth weight (LBW).
  
  
  RESULTS
  Pregnant women tended to move to areas with lower levels of PM10. For all outcomes, there was negligible difference between effect sizes corresponding to exposures calculated with first, last and full address histories. For LBW, associations were observed for exposure in second trimester (OR 1.09; 95% CI: 1.04-1.14 per 1μg/m(3) PM10) and whole pregnancy (OR 1.08; 95% CI: 1.02-1.14). For SGA, associations were observed for elevated exposure in second trimester (OR 1.02; 95% CI: 1.00-1.04) and whole pregnancy (OR 1.03; 95% CI: 1.01-1.05). There was insufficient evidence for association with preterm birth.
  
  
  CONCLUSIONS
  PM10 was associated with both SGA and term LBW. However, there was negligible benefit in accounting for residential mobility in pregnancy in this study.
authors.affiliation: School of Public Health, Curtin University, Perth, WA 6845, Australia. Electronic address: gavin.f.pereira@curtin.edu.au.
authors.forename: Gavin
authors.initials: G
authors.lastname: Pereira
authors.affiliation: Center for Perinatal Pediatric and Environmental Epidemiology, School of Medicine, Yale University, New Haven, CT 06511, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Bracken
authors.affiliation: School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Bell
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D003237:Connecticut; D005260:Female; D047109:Fetal Development / Q000187:drug effects*; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016015:Logistic Models; D010316:Particle Size; D052638:Particulate Matter / Q000008:administration & dosage / Q000009:adverse effects*; D011157:Population Dynamics / Q000706:statistics & numerical data; D011247:Pregnancy; D012189:Retrospective Studies
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Exposure misclassification; Fetal growth; Pregnancy; Preterm birth; Residential mobility