Maternal Exposure to Particulate Air Pollution and Term Birth Weight: A Multi-Country Evaluation of Effect and Heterogeneity

Payam Dadvand,^1,2,3 Jennifer Parker,⁴ Michelle L. Bell,⁵ Matteo Bonzini,⁶ Michael Brauer,⁷ Lyndsey A. Darrow,⁸ Ulrike Gehring,⁹ Svetlana V. Glinianaia,¹⁰ Nelson Gouveia,¹¹ Eun-hee Ha,¹² Jong Han Leem,¹³ Edith H. van den Hooven,^14,15 Bin Jalaludin,^16,17,18 Bill M. Jesdale,¹⁹ Johanna Lepeule,^20,21,22 Rachel Morello-Frosch,^19,23 Geoffrey G. Morgan,^24,25 Angela Cecilia Pesatori,²⁶ Frank H. Pierik,¹⁵ Tanja Pless-Mulloli,¹⁰ David Q. Rich,²⁷ Sheela Sathyanarayana,²⁸ Juhee Seo,¹² Rémy Slama,^21,22 Matthew Strickland,⁸ Lillian Tamburic,²⁹ Daniel Wartenberg,³⁰ Mark J. Nieuwenhuijsen,^1,2,3 and Tracey J. Woodruff³¹

¹Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; ²Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona, Spain; ³CIBER Epidemiologia y Salud Pública (CIBERESP), Spain; ⁴National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland, USA; ⁵School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA; ⁶Department of Clinical and Experimental Medicine, University of Insubria, Varese, Italy; ⁷University of British Columbia, School of Population and Public Health, Vancouver, British Columbia, Canada; ⁸Department of Environmental Health, Emory University, Atlanta, Georgia, USA; ⁹Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands; ¹⁰Institute of Health & Society, Newcastle University, Newcastle upon Tyne, United Kingdom; ¹¹Department of Preventive Medicine, School of Medicine of the University of São Paulo, São Paulo, Brazil; ¹²Department of Preventive Medicine, Ewha Womans University, Seoul, Republic of Korea; ¹³Department of Occupational and Environmental Medicine, Inha University, Incheon, Republic of Korea; ¹⁴Generation R Study Group, Erasmus Medical Center, Rotterdam, the Netherlands; ¹⁵Urban Environment and Safety, TNO, Utrecht, the Netherlands; ¹⁶Centre for Research, Evidence Management and Surveillance, Sydney, Australia; ¹⁷South Western Sydney Local Health Districts, Sydney, Australia; ¹⁸School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia; ¹⁹Department of Environmental Science, Policy, and Management, University of California–Berkeley, Berkeley, California, USA; ²⁰Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; ²¹Team of Environmental Epidemiology Applied to Reproduction and Respiratory Health, INSERM, and ²²Grenoble University, U823, Institut Albert Bonniot, Grenoble, France; ²³School of Public Health, University of California–Berkeley, Berkeley, California, USA; ²⁴North Coast Area Health Service, Lismore, New South Wales, Australia; ²⁵University Centre for Rural Health–North Coast, University of Sydney, Sydney, Australia; ²⁶Department of Occupational and Environmental Health, Università di Milano, Milan, Italy; ²⁷Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; ²⁸Seattle Children’s Research Institute, University of Washington, Seattle, Washington, USA; ²⁹Centre for Health Services and Policy Research, University of British Columbia, Vancouver, Canada; ³⁰UMDNJ–Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; ³¹Center for Reproductive Health and the Environment, University of California–San Francisco, San Francisco, California, USA

Abstract

Background: A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent.

Objectives: We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association.

Methods: Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM₁₀ and PM_2.5 (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates.

Results: In random-effects meta-analyses, term LBW was positively associated with a 10-μg/m³ increase in PM₁₀ [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM_2.5 (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-μg/m³ increase in PM₁₀ exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (–8.9 g; 95% CI: –13.2, –4.6 g). Meta-regressions revealed that centers with higher median PM_2.5 levels and PM_2.5:PM₁₀ ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations.

Conclusion: Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.

Key words: air pollution, fetal growth, heterogeneity, ICAPPO, low birth weight, meta-analysis, meta-regression, multi-center study, particulate matter, pregnancy.

Environ Health Perspect 121:367–373 (2013). http://dx.doi.org/10.1289/ehp.1205575 [Online 6 February 2013]

Address correspondence to P. Dadvand, CREAL, Barcelona Biomedical Research Park, Dr. Aiguader, 88, 08003 Barcelona, Spain. Telephone: 34 93 214 7317. E-mail: pdadvand@creal.cat

Supplemental Material is available online (http://dx.doi.org/10.1289/ehp.1205575).

We are grateful to D. Martinez, J. Grellier, and P. Grillo for their contributions to the analytical parts of the paper.

This project was supported by the U.S. Environmental Protection Agency under contract number EP-W-05-022 and by the National Institute of Environmental Health Sciences (R01ES016317, R01ES019587). For the Vancouver analysis, the British Columbia (BC) Ministry of Health, the BC Vital Statistics Agency, and the BC Reproductive Care Program approved access to and use of the data facilitated by Population Data BC. The U.K. PAMPER study was supported by the Wellcome Trust (grant 072465/Z/03/Z). P.D. is funded by a Juan de la Cierva fellowship (JCI-2011-09937) awarded by the Spanish Ministry of Science and Innovation.

The authors declare they have no actual or potential competing financial interests.

Received 5 June 2012; Accepted 28 December 2012; Online 6 February 2013.