Background Maternal exposure to ambient air pollution has been associated with higher risk of preterm birth and reduced fetal growth, but heterogeneity among prior studies suggests that additional studies are needed in diverse populations and settings. We examined the associations between maternal ambient air pollution levels, risk of preterm birth and markers of fetal growth in an urban population with relatively low exposure to air pollution.
Methods We linked 61 640 mother–infant pairs who delivered at a single hospital in Providence, Rhode Island, from 2002 to 2012 to birth certificate and hospital discharge data. We used spatial-temporal models and stationary monitors to estimate exposure to fine particulate matter (PM2.5) and black carbon (BC) during pregnancy. Using generalised linear models, we evaluated the association between pollutant levels, risk of preterm birth and markers of fetal growth.
Results In adjusted models, an IQR (2.5 µg/m3) increase in pregnancy-average PM2.5 was associated with ORs of preterm birth of 1.04 (95% CI 0.94 to 1.15) and 0.86 (0.76 to 0.98) when considering modelled and monitored PM2.5, respectively. An IQR increase in modelled and monitored PM2.5 was associated with a 12.1 g (95% CI −24.2 to –0.1) and 15.9 g (95% CI −31.6 to –0.3) lower birth weight. Results for BC were highly sensitive to choice of exposure metric.
Conclusion In a population with relatively low exposures to ambient air pollutants, PM2.5 was associated with reduced birth weight but not with risk of preterm birth.
- air pollution
- birth weight
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Contributors GAW, CJM, KTK and SLK conceived the study. YAA and JDS provided exposure assessment expertise and exposure estimates. Analyses were conducted by SLK and MNE. Additional methodological and substantive consultation was provided by DAS, KG and JDS. SLK, KG and MNE drafted the manuscript, tables and supplemental material. All authors reviewed, edited and approved the final manuscript.
Funding This work was supported by grant R21-ES023073 from the National Institute of Environmental Health Sciences (National Institutes of Health), US Environmental Protection Agency grant RD83479801 and a doctoral fellowship from the Institute at Brown for Environment and Society.
Disclaimer The contents of this report are solely the responsibility of the authors and do not necessarily represent the official views of the sponsoring organisations.
Competing interests None declared.
Ethics approval Study approval was obtained from Brown University, Women and Infants Hospital of Rhode Island and the Rhode Island Department of Health.
Provenance and peer review Not commissioned; externally peer reviewed.