| Birth Outcomes and Prenatal Exposure to Ozone, Carbon Monoxide, and Particulate Matter: Results from the Children's Health Study Muhammad T. Salam,1 Joshua Millstein,1 Yu-Fen Li,1 Frederick W. Lurmann,2 Helene G. Margolis,3 and Frank D. Gilliland1 1Department of Preventive Medicine, University of Southern California, Keck School of Medicine, Los Angeles, California, USA; 2Sonoma Technology Inc., Petaluma, California, USA; 3Air Resources Board, State of California, Sacramento, California, USA Abstract
Exposures to ambient air pollutants have been associated with adverse birth outcomes. We investigated the effects of air pollutants on birth weight mediated by reduced fetal growth among term infants who were born in California during 1975-1987 and who participated in the Children's Health Study. Birth certificates provided maternal reproductive history and residence location at birth. Sociodemographic factors and maternal smoking during pregnancy were collected by questionnaire. Monthly average air pollutant levels were interpolated from monitors to the ZIP code of maternal residence at childbirth. Results from linear mixed-effects regression models showed that a 12-ppb increase in 24-hr ozone averaged over the entire pregnancy was associated with 47.2 g lower birth weight [95% confidence interval (CI) , 27.4-67.0 g], and this association was most robust for exposures during the second and third trimesters. A 1.4-ppm difference in first-trimester carbon monoxide exposure was associated with 21.7 g lower birth weight (95% CI, 1.1-42.3 g) and 20% increased risk of intrauterine growth retardation (95% CI, 1.0-1.4) . First-trimester CO and third-trimester O3 exposures were associated with 20% increased risk of intrauterine growth retardation. A 20-µg/m3 difference in levels of particulate matter ≤ 10 µm in aerodynamic diameter (PM10) during the third trimester was associated with a 21.7-g lower birth weight (95% CI, 1.1-42.2 g) , but this association was reduced and not significant after adjusting for O3. In summary, O3 exposure during the second and third trimesters and CO exposure during the first trimester were associated with reduced birth weight. Key words: air pollution, birth weight, carbon monoxide, intrauterine growth retardation, maternal exposure, nitrogen dioxide, ozone, particulate matter. Environ Health Perspect 113: 1638-1644 (2005) . doi:10.1289/ehp.8111 available via http://dx.doi.org/ [Online 18 July 2005]
Address correspondence to F.D. Gilliland, Department of Preventive Medicine, USC Keck School of Medicine, 1540 Alcazar St., CHP 236, Los Angeles, CA 90033 USA. Telephone: (323) 442-1096. Fax: (323) 442-3272. E-mail: gillilan@usc.edu Supplemental material is available online at http://ehp.niehs.nih.gov/members/2005/8111/supplemental.pdf We thank S.H. Alcorn for technical assistance in estimating air pollution levels. This research was funded by the National Institute of Environmental Health Sciences (grants 5P01 ES009581, 5P01 ES011627, and 5P30 ES07048) ; the U.S. Environmental Protection Agency (grants R826708-01 and RD831861-01) ; the National Heart, Lung, and Blood Institute (grant 5R01HL61768) ; the California Air Resources Board (contract 94-331) ; and the Hastings Foundation. The authors declare they have no competing financial interests. Received 9 March 2005 ; accepted 18 July 2005.
The full version of this article is available for free in HTML or PDF formats. |
