Influence of the Urban Exposome on Birth Weight

Background: The exposome is defined as the totality of environmental exposures from conception onwards. It calls for providing a holistic view of environmental exposures and their effects on human health by evaluating multiple environmental exposures simultaneously during critical periods of life. Objective: We evaluated the association of the urban exposome with birth weight. Methods: We estimated exposure to the urban exposome, including the built environment, air pollution, road traffic noise, meteorology, natural space, and road traffic (corresponding to 24 environmental indicators and 60 exposures) for nearly 32,000 pregnant women from six European birth cohorts. To evaluate associations with either continuous birth weight or term low birth weight (TLBW) risk, we primarily relied on the Deletion-Substitution-Addition (DSA) algorithm, which is an extension of the stepwise variable selection method. Second, we used an exposure-by-exposure exposome-wide association studies (ExWAS) method accounting for multiple hypotheses testing to report associations not adjusted for coexposures. Results: The most consistent statistically significant associations were observed between increasing green space exposure estimated as Normalized Difference Vegetation Index (NDVI) and increased birth weight and decreased TLBW risk. Furthermore, we observed statistically significant associations among presence of public bus line, land use Shannon's Evenness Index, and traffic density and birth weight in our DSA analysis. Conclusion: This investigation is the first large urban exposome study of birth weight that tests many environmental urban exposures. It confirmed previously reported associations for NDVI and generated new hypotheses for a number of built-environment exposures. The study has received funding from the European Community’s Seventh Framework Programme (FP7/2007–2013) under Grant Agreement No. 308333—the HELIX project—for data collection and analyses. The HELIX program built on six existing cohorts that received previous funding, including the major cohorts listed here. INMA data collections were supported by grants from the Instituto de Salud Carlos III, CIBERESP, the Conselleria de Sanitat, Generalitat Valenciana, Department of Health of the Basque Government; the Provincial Government of Gipuzkoa, and the Generalitat de Catalunya-CIRIT. KANC was funded by the grant of the Lithuanian Agency for Science Innovation and Technology (6-04-2014_31V-66). MoBa (Norwegian Mother and Child Cohort Study) is supported by the Norwegian Ministry of Health and the Ministry of Education and Research, NIH/NIEHS (Contract No. N01-ES-75558), and the U.S. National Institutes of Health (NIH) National Institute of Environmental Health Sciences (NIEHS; Contract No. N01-ES-75558), and National Institute of Neurological Disorders and Stroke (Grant No. 1 UO1 NS 047537-01 and Grant No. 2 UO1 NS 047537-06A1). The Rhea project was financially supported by European projects (EU FP6–2003-Food-3-NewGeneris, EU FP6.STREP Hiwate, EU FP7 ENV.2007·1.2.2.2, Project No. 211250 Escape, EU FP7–2008-ENV-1·2.1·4 Envirogenomarkers, EU FP7-HEALTH-2009-single stage CHICOS, EU FP7 ENV.2008.1.2.1.6, Proposal No. 226285 ENRIECO, EUFP7-HEALTH-2012 Proposal No. 308333 HELIX, FP7 European Union Project No. 264357 MeDALL), and the Greek Ministry of Health (Program of Prevention of Obesity and Neurodevelopmental Disorders in Preschool Children, in Heraklion district, Crete, Greece: 2011–2014; “Rhea Plus”: Primary Prevention Program of Environmental Risk Factors for Reproductive Health, and Child Health: 2012–15). L.C. received additional funding from the Southern California Environmental Health Sciences Center (Grant No. P30ES007048) funded by NIEHS. We acknowledge the support of the program for international scientific collaborations of Région Rhône-Alpes-Auvergne.