Ambient Air Pollution and Pregnancy Outcomes: A Review of the Literature Radim J. Srám,1 Blanka Binková,1 Jan Dejmek,1 and Martin Bobak2 1Laboratory of Genetic Ecotoxicology, Institute of Experimental Medicine, Academy of Sciences, and Health Institute of Central Bohemia, Prague, Czech Republic; 2Department of Epidemiology and Public Health, University College London, London, United Kingdom Abstract Over the last decade or so, a large number of studies have investigated the possible adverse effects of ambient air pollution on birth outcomes. We reviewed these studies, which were identified by a systematic search of the main scientific databases. Virtually all reviewed studies were population based, with information on exposure to air pollution derived from routine monitoring sources. Overall, there is evidence implicating air pollution in adverse effects on different birth outcomes, but the strength of the evidence differs between outcomes. The evidence is sufficient to infer a causal relationship between particulate air pollution and respiratory deaths in the postneonatal period. For air pollution and birth weight the evidence suggests causality, but further studies are needed to confirm an effect and its size and to clarify the most vulnerable period of pregnancy and the role of different pollutants. For preterm births and intrauterine growth retardation (IUGR) the evidence as yet is insufficient to infer causality, but the available evidence justifies further studies. Molecular epidemiologic studies suggest possible biologic mechanisms for the effect on birth weight, premature birth, and IUGR and support the view that the relation between pollution and these birth outcomes is genuine. For birth defects, the evidence base so far is insufficient to draw conclusions. In terms of exposure to specific pollutants, particulates seem the most important for infant deaths, and the effect on IUGR seems linked to polycyclic aromatic hydrocarbons, but the existing evidence does not allow precise identification of the different pollutants or the timing of exposure that can result in adverse pregnancy outcomes. Key words: air pollution, intrauterine growth retardation, low birth weight, molecular epidemiology, PAHs, particulate matter, PM10, premature birth, reproductive effects, SO2. Environ Health Perspect 113:375-382 (2005) . doi:10.1289/ehp.6362 available via http://dx.doi.org/ [Online 4 January 2005] Address correspondence to R.J. Sˇrám, Laboratory of Genetic Ecotoxicology, Institute of Experimental Medicine AS CR, 142 20 Prague 4, Vídeòská 1083, Czech Republic. Telephone: 420-241-062-596. Fax: 420-241-062-785. E-mail: sram@biomed.cas.cz We thank T. Damstra (World Health Organization, Research Triangle Park, NC, USA) for her critical comments. This work was supported by the grants from the European Commission (QLRT-2001-02198, ChildrenGenonetwork) and the Ministry of Environment of the Czech Republic (VaV 740/5/03) . The authors declare they have no competing financial interests. Received 31 March 2003 ; accepted 4 January 2005. The full version of this article is available for free in HTML or PDF formats. |