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 is suggestive of causality, although further studies are needed. For preterm births and 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 PAHs, but the existing evidence does not allow precise identification of the different pollutants and the timing of exposure that can result in adverse pregnancy outcomes.
On the basis of this review, we suggest several priorities for future research. First, it remains to be confirmed that the effects on birth weight, prematurity, and IUGR are genuine and causal. Second, it is important to identify the most vulnerable period of exposure in pregnancy. Third, the contribution of different pollutants needs to be established. Fourth, the biologic pathways require further clarification. And finally, with the increasing attention to the life course, it would be interesting to examine whether early exposures and impaired reproductive outcome have any long-term consequences in later life.
We thank T. Damstra (World Health Organization, Research Triangle Park, NC, USA) for her critical comments.Funding information
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).
R.J. Srám, 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: firstname.lastname@example.org .
Environ Health Perspect. 2005;113(4):378-382. © 2005 National Institute of Environmental Health Sciences
Cite this: Ambient Air Pollution and Pregnancy Outcomes: A Review of the Literature - Medscape - Apr 01, 2005.