title: Exposure to fine particulate matter during pregnancy and risk of preterm birth among women in New Jersey, Ohio, and Pennsylvania, 2000-2005.
abstract: BACKGROUND
  Particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) has been variably associated with preterm birth (PTB).
  
  
  OBJECTIVE
  We classified PTB into four categories (20-27, 28-31, 32-34, and 35-36 weeks completed gestation) and estimated risk differences (RDs) for each category in association with a 1-μg/m3 increase in PM2.5 exposure during each week of gestation.
  
  
  METHODS
  We assembled a cohort of singleton pregnancies that completed ≥ 20 weeks of gestation during 2000-2005 using live birth certificate data from three states (Pennsylvania, Ohio, and New Jersey) (n = 1,940,213; 8% PTB). We estimated mean PM2.5 exposures for each week of gestation from monitor-corrected Community Multi-Scale Air Quality modeling data. RDs were estimated using modified Poisson linear regression and adjusted for maternal race/ethnicity, marital status, education, age, and ozone.
  
  
  RESULTS
  RD estimates varied by exposure window and outcome period. Average PM2.5 exposure during the fourth week of gestation was positively associated with all PTB outcomes, although magnitude varied by PTB category [e.g., for a 1-μg/m3 increase, RD = 11.8 (95% CI: -6, 29.2); RD = 46 (95% CI: 23.2, 68.9); RD = 61.1 (95% CI: 22.6, 99.7); and RD = 28.5 (95% CI: -39, 95.7) for preterm births during 20-27, 28-31, 32-34, and 35-36 weeks, respectively]. Exposures during the week of birth and the 2 weeks before birth also were positively associated with all PTB categories.
  
  
  CONCLUSIONS
  Exposures beginning around the time of implantation and near birth appeared to be more strongly associated with PTB than exposures during other time periods. Because particulate matter exposure is ubiquitous, evidence of effects of PM2.5 exposure on PTB, even if small in magnitude, is cause for concern.
authors.affiliation: Department of Epidemiology, UNC Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Rappazzo
authors.forename: Julie L
authors.initials: JL
authors.lastname: Daniels
authors.forename: Lynne C
authors.initials: LC
authors.lastname: Messer
authors.forename: Charles
authors.initials: C
authors.lastname: Poole
authors.forename: Danelle T
authors.initials: DT
authors.lastname: Lobdell
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D062305:Geographic Mapping; D006801:Humans; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D009515:New Jersey / Q000453:epidemiology; D009820:Ohio / Q000453:epidemiology; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis; D010414:Pennsylvania / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology*; D012307:Risk Factors
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter