Ambient Air Pollution and Preterm Birth: A Time-series Analysis.
Darrow, Lyndsey A. a; Klein, Mitchel a; Flanders, W Dana a; Waller, Lance A. a; Correa, Adolfo b; Marcus, Michele a; Mulholland, James A. c; Russell, Armistead G. c; Tolbert, Paige E. a
20(5):689-698, September 2009.
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Background: An emerging body of evidence suggests that ambient levels of air pollution during pregnancy are associated with preterm birth.
Methods: To further investigate these relationships we used vital record data to construct a retrospective cohort of 476,489 births occurring between 1994 and 2004 in 5 central counties of metropolitan Atlanta. Using a time-series approach, we examined aggregated daily counts of preterm birth in relation to ambient levels of carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, particulate matter <10 [mu]m in diameter (PM10), particulate matter <2.5 [mu]m in diameter (PM2.5), and speciated PM measurements. Daily pollutant levels in 5-county Atlanta were characterized using a population-weighted spatial average of air quality monitors in the study area. We also examined ambient concentrations at individual monitors in analyses limited to mothers with residential geocodes within 4 miles of each monitor. Relationships between average pollution levels during 3 gestational windows of interest were modeled using Poisson generalized linear models. Results were adjusted for seasonal and long-term time trends.
Results: Although most results were null, there were 3 positive associations between ambient pollution levels and preterm birth in the 4-mile capture-area analyses. Daily preterm birth rates were associated with average NO2 concentrations in the preceding 6 weeks and with average PM2.5 sulfate and PM2.5 water-soluble metal concentrations in the preceding week.
Conclusions: Results provide limited support for late-pregnancy effects of ambient air pollution on preterm birth.
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