Date of this Version
A range of health effects, including adverse pregnancy outcomes, have been associated with exposure to ambient concentrations of particulate matter (PM) and ozone(O3). The objective of this study was to determine whether maternal exposure to fine particulate matter (PM2.5) andO3 during pregnancy is associated with the risk of term low birth weight and small for gestational age infants in both single and co-pollutant models. Term low birth weight and small for gestational age were determined using all birth certificates from North Carolina from 2003 to 2005. Ambient air concentrations of PM2.5 and O3 were predicted using a hierarchical Bayesian model of air pollution that combined modeled air pollution estimates from the EPA's Community Multi-Scale Air Quality (CMAQ) model with air monitor data measured by the EPA's Air Quality System. Binomial regression, adjusted for multiple potential confounders, was performed. In adjusted single-pollutant models for the third trimester, O3 concentration was positively associated with small for gestational age and term low birth weight births [risk ratios for an interquartile range increase inO3: 1.16(95%CI1.11,1.22)for small for gestational age and2.03(95% CI 1.80,2.30)for term low birth weight]; however, inverse or null associations were observed forPM2.5 [risk ratios for an interquartile range increase inPM2.5: 0.97(95%CI0.95,0.99) for small for gestational age and 1.01(95%CI0.97,1.06)for term low birth weight]. Findings were similar in co-pollutant models and linear models of birth weight. These results suggest thatO3 concentrations in both urban and rural areas may be associated with an increased risk of term low birth weight and small for gestational age births.