title: Maternal exposure to particulate air pollution and term birth weight: a multi-country evaluation of effect and heterogeneity.
abstract: BACKGROUND
  A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent.
  
  
  OBJECTIVE
  We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association.
  
  
  METHODS
  Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM(10) and PM(2.5) (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates.
  
  
  RESULTS
  In random-effects meta-analyses, term LBW was positively associated with a 10-μg/m3 increase in PM10 [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM(2.5) (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-μg/m3 increase in PM(10) exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (-8.9 g; 95% CI: -13.2, -4.6 g). Meta-regressions revealed that centers with higher median PM(2.5) levels and PM(2.5):PM(10) ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations.
  
  
  CONCLUSIONS
  Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.
authors: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain. pdadvand@creal.cat
authors: Payam
authors: P
authors: Dadvand
authors: Jennifer
authors: J
authors: Parker
authors: Michelle L
authors: ML
authors: Bell
authors: Matteo
authors: M
authors: Bonzini
authors: Michael
authors: M
authors: Brauer
authors: Lyndsey A
authors: LA
authors: Darrow
authors: Ulrike
authors: U
authors: Gehring
authors: Svetlana V
authors: SV
authors: Glinianaia
authors: Nelson
authors: N
authors: Gouveia
authors: Eun-hee
authors: EH
authors: Ha
authors: Jong Han
authors: JH
authors: Leem
authors: Edith H
authors: EH
authors: van den Hooven
authors: Bin
authors: B
authors: Jalaludin
authors: Bill M
authors: BM
authors: Jesdale
authors: Johanna
authors: J
authors: Lepeule
authors: Rachel
authors: R
authors: Morello-Frosch
authors: Geoffrey G
authors: GG
authors: Morgan
authors: Angela Cecilia
authors: AC
authors: Pesatori
authors: Frank H
authors: FH
authors: Pierik
authors: Tanja
authors: T
authors: Pless-Mulloli
authors: David Q
authors: DQ
authors: Rich
authors: Sheela
authors: S
authors: Sathyanarayana
authors: Juhee
authors: J
authors: Seo
authors: Rémy
authors: R
authors: Slama
authors: Matthew
authors: M
authors: Strickland
authors: Lillian
authors: L
authors: Tamburic
authors: Daniel
authors: D
authors: Wartenberg
authors: Mark J
authors: MJ
authors: Nieuwenhuijsen
authors: Tracey J
authors: TJ
authors: Woodruff
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D001724:Birth Weight; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D018811:Maternal Exposure; D010316:Particle Size
chemical_list: D000393:Air Pollutants
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