title: Sources of fine particulate matter and risk of preterm birth in Connecticut, 2000-2006: a longitudinal study.
abstract: BACKGROUND
  Previous studies have examined fine particulate matter (≤ 2.5 μm; PM2.5) and preterm birth, but there is a dearth of longitudinal studies on this topic and a paucity of studies that have investigated specific sources of this exposure.
  
  
  OBJECTIVE
  Our aim was to assess whether anthropogenic sources are associated with risk of preterm birth, comparing successive pregnancies to the same woman.
  
  
  METHODS
  Birth certificates were used to select women who had vaginal singleton live births at least twice in Connecticut during 2000-2006 (n = 23,123 women, n = 48,208 births). We procured 4,085 daily samples of PM2.5 on Teflon filters from the Connecticut Department of Environmental Protection for six cities in Connecticut. Filters were analyzed for chemical composition, and Positive Matrix Factorization was used to determine contributions of PM2.5 sources. Risk estimates were calculated with conditional logistic regression, matching pregnancies to the same women.
  
  
  RESULTS
  Odds ratios of preterm birth per interquartile range increase in whole pregnancy exposure to dust, motor vehicle emissions, oil combustion, and regional sulfur PM2.5 sources were 1.01 (95% CI: 0.93, 1.09), 1.01 (95% CI: 0.92, 1.10), 1.00 (95% CI: 0.89, 1.12), and 1.09 (95% CI: 0.97, 1.22), respectively.
  
  
  CONCLUSIONS
  This was the first study of PM2.5 sources and preterm birth, and the first matched analysis, that better addresses individual-level confounding potentially inherent in all past studies. There was insufficient evidence to suggest that sources were statistically significantly associated with preterm birth. However, elevated central estimates and previously observed associations with mass concentration motivate the need for further research. Future studies would benefit from high source exposure settings and longitudinal study designs, such as that adopted in this study.
authors.affiliation: Center for Perinatal Pediatric and Environmental Epidemiology, School of Medicine, Yale University, New Haven, Connecticut, USA.
authors.forename: Gavin
authors.initials: G
authors.lastname: Pereira
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Bell
authors.forename: Hyung Joo
authors.initials: HJ
authors.lastname: Lee
authors.forename: Petros
authors.initials: P
authors.lastname: Koutrakis
authors.forename: Kathleen
authors.initials: K
authors.lastname: Belanger
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D003237:Connecticut / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D018811:Maternal Exposure / Q000009:adverse effects / Q000706:statistics & numerical data; D016017:Odds Ratio; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects / Q000032:analysis*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D047928:Premature Birth / Q000139:chemically induced / Q000453:epidemiology*; D013455:Sulfur / Q000032:analysis; D014504:Urban Health; D001335:Vehicle Emissions / Q000032:analysis
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions; D013455:Sulfur