Abstract
Since the 2000s, air pollution has generally continued to decrease in the U.S. To investigate preterm birth (PTB) risk associated with air pollutants in two consecutive pregnancies, we estimated exposures using modified Community Multiscale Air Quality models linked to the NICHD Consecutive Pregnancy Study. Electronic medical records for delivery admissions were available for 50,005 women with singleton births in 20 Utah-based hospitals between 2002–2010. We categorized whole pregnancy average exposures as high (>75th percentile), moderate (25–75) and low (<25). Modified Poisson regression estimated second pregnancy PTB risk associated with persistent high and moderate exposure, and increasing or decreasing exposure, compared to persistent low exposure. Analyses were adjusted for prior PTB, interpregnancy interval and demographic and clinical characteristics. Second pregnancy PTB risk was increased when exposure stayed high for sulfur dioxide (32%), ozone (17%), nitrogen oxides (24%), nitrogen dioxide (43%), carbon monoxide (31%) and for particles < 10 microns (29%) versus consistently low exposure. PTB risk tended to increase to a lesser extent for repeated PTB (19–21%) than for women without a prior PTB (22–79%) when exposure increased or stayed high. Area-level changes in air pollution exposure appear to have important consequences in consecutive pregnancies with increasing exposure associated with higher risk.
Highlights
Preterm birth has been associated with air pollution exposure, but no prior studies have examined the change in risk over time in an existing cohort
Second pregnancy preterm births were more common among older mothers, women with slightly shorter inter-pregnancy intervals, non-white women, those who were unmarried and had public insurance, as well as mothers who were multiparous and reported smoking and alcohol use during pregnancy
As anticipated, having a prior preterm birth was associated with a higher proportion of preterm birth in the second pregnancy (30.6%) compared with a prior term birth (5.7%)
Summary
Preterm birth has been associated with air pollution exposure, but no prior studies have examined the change in risk over time in an existing cohort. Contains detailed clinical data on deliveries for more than 50,000 women with at least two pregnancies during the study period [1]. Criteria air pollutants in the United States (U.S.) decreased over the 2000’s [2] while the preterm birth rate peaked in 2006 at 12.8% and declined to 11.9% in. During this period of dynamic change, we evaluated the air-pollution associated preterm birth risk in this cohort of low-risk women. Considering that continued progress to improve air quality is challenged by the global impact of extreme weather events and climate change, which may increase pollution after decades of. Public Health 2019, 16, 3365; doi:10.3390/ijerph16183365 www.mdpi.com/journal/ijerph
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