| Exposures to Air Pollutants during Pregnancy and Preterm Delivery Jong-Han Leem,1,2 Brian M. Kaplan,3 Youn K. Shim,3 Hana R. Pohl,2 Carol A. Gotway,4 Stevan M. Bullard,3 J. Felix Rogers,5 Melissa M. Smith,3 and Carolyn A. Tylenda2 1Department of Occupational and Environmental Medicine, Inha University, Incheon, Korea; 2Division of Toxicology and Environmental Medicine, and 3Division of Health Studies, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia, USA; 4Division of Environmental Hazards and Health Effects Biometry Activity, National Center for Environmental Health, and 5Office of Science, Office of the Director, National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Georgia, USA Abstract
The association between preterm delivery (PTD) and exposure to air pollutants has recently become a major concern. We investigated this relationship in Incheon, Republic of Korea, using spatial and temporal modeling to better infer individual exposures. The birth cohort consisted of 52,113 singleton births in 2001–2002, and data included residential address, gestational age, sex, birth date and order, and parental age and education. We used a geographic information system and kriging methods to construct spatial and temporal exposure models. Associations between exposure and PTD were evaluated using univariate and multivariate log-binomial regressions. Given the gestational age, birth date, and the mother's residential address, we estimated each mother's potential exposure to air pollutants during critical periods of the pregnancy. The adjusted risk ratios for PTD in the highest quartiles of the first trimester exposure were 1.26 [95% confidence interval (CI) , 1.11–1.44] for carbon monoxide, 1.27 (95% CI, 1.04–1.56) for particulate matter with aerodynamic diameter ≤ 10 µm, 1.24 (95% CI, 1.09–1.41) for nitrogen dioxide, and 1.21 (95% CI, 1.04–1.42) for sulfur dioxide. The relationships between PTD and exposures to CO, NO2, and SO2 were dose dependent (p < 0.001, p < 0.02, p < 0.02, respectively) . In addition, the results of our study indicated a significant association between air pollution and PTD during the third trimester of pregnancy. In conclusion, our study showed that relatively low concentrations of air pollution under current air quality standards during pregnancy may contribute to an increased risk of PTD. A biologic mechanism through increased prostaglandin levels that are triggered by inflammatory mediators during exposure periods is discussed. Key words: adverse birth outcomes, exposure, geographic information system, GIS, Korea, kriging methods, risk assessment, susceptibility. Environ Health Perspect 114: 905–910 (2006) . doi:10.1289/ehp.8733 available via http://dx.doi.org/ [Online 16 February 2006]
Address correspondence to J.-H. Leem, Department of Occupational and Environmental Medicine, Inha University, 7-206 3rd St., Shinheung dong, Jung gu, Incheon, Korea. Telephone: 82-32-890-2861. Fax: 82-32-890-2859. E-mail: ekeeper@inha.ac.kr This study is entirely supported by Inha University Research Fund. The authors declare they have no competing financial interests. Received 12 October 2005 ; accepted 16 February 2006.
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