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Open Access Research

Particulate matter exposure during pregnancy is associated with birth weight, but not gestational age, 1962-1992: a cohort study

Mark S Pearce1*, Svetlana V Glinianaia1, Rakesh Ghosh2, Judith Rankin1, Steven Rushton3, Martin Charlton4, Louise Parker5 and Tanja Pless-Mulloli13

Author Affiliations

1 Institute of Health and Society, Newcastle University, Newcastle upon Tyne, England, UK

2 Department of Public Health Sciences, University of California, Davis, California, USA

3 Newcastle Institute for Research on Sustainability, Newcastle University, Newcastle upon Tyne, England, UK

4 National Centre for Geocomputation, National University of Ireland, Maynooth, Ireland

5 Departments of Medicine and Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada

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Environmental Health 2012, 11:13  doi:10.1186/1476-069X-11-13

Published: 9 March 2012

Abstract

Background

Exposure to air pollutants is suggested to adversely affect fetal growth, but the evidence remains inconsistent in relation to specific outcomes and exposure windows.

Methods

Using birth records from the two major maternity hospitals in Newcastle upon Tyne in northern England between 1961 and 1992, we constructed a database of all births to mothers resident within the city. Weekly black smoke exposure levels from routine data recorded at 20 air pollution monitoring stations were obtained and individual exposures were estimated via a two-stage modeling strategy, incorporating temporally and spatially varying covariates. Regression analyses, including 88,679 births, assessed potential associations between exposure to black smoke and birth weight, gestational age and birth weight standardized for gestational age and sex.

Results

Significant associations were seen between black smoke and both standardized and unstandardized birth weight, but not for gestational age when adjusted for potential confounders. Not all associations were linear. For an increase in whole pregnancy black smoke exposure, from the 1st (7.4 μg/m3) to the 25th (17.2 μg/m3), 50th (33.8 μg/m3), 75th (108.3 μg/m3), and 90th (180.8 μg/m3) percentiles, the adjusted estimated decreases in birth weight were 33 g (SE 1.05), 62 g (1.63), 98 g (2.26) and 109 g (2.44) respectively. A significant interaction was observed between socio-economic deprivation and black smoke on both standardized and unstandardized birth weight with increasing effects of black smoke in reducing birth weight seen with increasing socio-economic disadvantage.

Conclusions

The findings of this study progress the hypothesis that the association between black smoke and birth weight may be mediated through intrauterine growth restriction. The associations between black smoke and birth weight were of the same order of magnitude as those reported for passive smoking. These findings add to the growing evidence of the harmful effects of air pollution on birth outcomes.

Keywords:
Black smoke; Particulate matter; Air pollution; Birth weight; Gestational age