Ambient air pollution and preterm birth: a time-series analysis
Lyndsey A Darrow1, Mitchel Klein, W Dana Flanders
1Rollins School of Public Health, Emory University, Atlanta, GA, USA. ldarrow@sph.emory.edu
Insights
Exposure to air pollution during pregnancy may increase preterm birth risk. Specific pollutants like nitrogen dioxide and PM2.5 components showed associations in late pregnancy.
Area of Science:
- Environmental Epidemiology
- Reproductive Health
- Air Quality Science
Background:
- Growing evidence links prenatal air pollution exposure to adverse birth outcomes.
- Preterm birth remains a significant public health concern globally.
Purpose of the Study:
- To investigate the association between ambient air pollution and preterm birth.
- To examine specific pollutants and gestational windows of vulnerability.
Main Methods:
- Retrospective cohort study of 476,489 births in Atlanta (1994-2004).
- Time-series analysis of daily preterm births and air pollutants (CO, NO2, SO2, O3, PM10, PM2.5).
- Poisson generalized linear models adjusted for time trends.
Main Results:
- Limited positive associations found between ambient pollution and preterm birth.
- Nitrogen dioxide (NO2) and PM2.5 components (sulfate, water-soluble metals) linked to preterm birth in the preceding week/6 weeks.
Conclusions:
- Findings offer limited support for late-pregnancy air pollution effects on preterm birth.
- Highlights potential role of specific pollutants in adverse pregnancy outcomes.
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 microm in diameter (PM10), particulate matter <2.5 microm 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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