BACKGROUND: Women of reproductive age can be exposed to endocrine-disrupting chemicals (EDCs) at work, and exposure to EDCs in pregnancy may affect fetal growth. OBJECTIVES: We assessed whether maternal occupational exposure to EDCs during pregnancy as classified by application of a job exposure matrix was associated with birth weight, term low birth weight (LBW), length of gestation, and preterm delivery. METHODS: Using individual participant data from 133,957 mother-child pairs in 13 European cohorts spanning births from 1994 through 2011, we linked maternal job titles with exposure to 10 EDC groups as assessed through a job exposure matrix. For each group, we combined the two levels of exposure categories (possible and probable) and compared birth outcomes with the unexposed group (exposure unlikely). We performed meta-analyses of cohort-specific estimates. RESULTS: Eleven percent of pregnant women were classified as exposed to EDCs at work during pregnancy, based on job title. Classification of exposure to one or more EDC group was associated with an increased risk of term LBW [odds ratio (OR) = 1.25; 95% CI: 1.04, 1.49], as were most specific EDC groups; this association was consistent across cohorts. Further, the risk increased with increasing number of EDC groups (OR = 2.11; 95% CI: 1.10, 4.06 for exposure to four or more EDC groups). There were few associations (p < 0.05) with the other outcomes; women holding job titles classified as exposed to bisphenol A or brominated flame retardants were at higher risk for longer length of gestation. CONCLUSION: Results from our large population-based birth cohort design indicate that employment during pregnancy in occupations classified as possibly or probably exposed to EDCs was associated with an increased risk of term LBW.

This work was supported by the European Community’s Seventh Framework Programme (grants FP7/2007-2013, 226285, 241604) as part of the Environmental Health Risks in European Birth Cohorts project (http://www.enrieco.org) and the Developing a Child Cohort Research Strategy for Europe project (http://www.chicosproject.eu); and by the Instituto de Salud Carlos III (grant CD12/00563). Funding per cohort: ABCD: This work was supported by the Netherlands Organization for Health Research and Development (grant 2100.0076). BAMSE: This work was supported by the Swedish Heart-Lung Foundation; Stockholm County Council; Swedish Research Council for Health, Working Life and Welfare; and the European Commission’s Seventh Framework 29 Program: the Mechanisms of the Development of Allergy (grant 261357). DNBC: This work was supported by the Danish Epidemiology of Science Centre; Pharmacy Foundation; Egmont Foundation; March of Dimes Birth Defect Foundation; Agustinus Foundation; and the Health Foundation. Generation R: This work was supported by the Erasmus Medical Center Rotterdam; Netherlands Organization for Health Research and Development; European Commission Seventh Framework Programme; and the Contaminant Mixtures and Human Reproductive Health Project (grant 212502); V.J. received an additional grant from the Netherlands Organization for Health Research and Development (grant VIDI 016.136.361) and Consolidator Grant from the European Research Council (grant ERC-2014-CoG-648916). Generation XXI: This work was supported by the Programa Operacional de Saúde – Saúde XXI; Quadro Comunitário de Apoio III; Administração Regional de Saúde Norte (Regional Department of Ministry of Health); Portuguese Foundation for Science and Technology; Fundo Europeu de Desenvolvimento Regional, and the Calouste Gulbenkian Foundation. INMA_Granada: This work was supported by the Instituto de Salud Carlos III (grants G03/176, CB06/02/0041); Spanish Ministry of Health (grant FIS-07/0252); European Union Commission (grants QLK4-1999-01422, QLK4-2002-00603, FP7-ENV-212502); and the Consejería de Salud de la Junta de Andalucía (grant 183/07; 0675-2010). INMA_New: This work was supported by the European Union (grants FP7-ENV-2011, 282957, HEALTH.2010.2.4.5-1); Instituto de Salud Carlos III (grants G03/176, CB06/02/0041, FIS-FEDER 03/1615, 04/1509, 04/1112, 04/1931, 05/1079, 05/1052, 06/1213, 07/0314, 09/02647, 11/01007, 11/02591, CP11/00178, FIS-PI06/0867, FIS-PS09/00090); Conselleria de Sanitat Generalitat Valenciana; Spanish Ministry of Health (grants FIS-PI041436, FIS- PI081151, FIS-PI042018, FIS-PI09/02311); Generalitat de Catalunya (grants CIRIT1999SGR, 00241); Obre Social Cajastur; Universidad de Oviedo; Department of Health of the Basque Government (grants 2005111093, 2009111069); and the Provincial Government of Gipuzkoa (grants DFG06/004, DFG08/001). KANC: This work was supported by the European Commission (grant FP6-036224). MoBa: This work was supported by the Norwegian Ministry of Health; National Institutes of Health; National Institute of Environmental Health Sciences (grant N01-ES–85433); National Institute of Neurological Disorders and Stroke (grant 1 UO1 NS 047537); Norwegian Research Council; Functional Genomics (grant 151918/S10); and Environmental Exposures and Health Outcomes (grant 213148). NINFEA: This work was supported by the Compagnia San Paolo Foundation, and by the Piedmont Region. Pélagie: This work was supported by the National Institute of Health and Medical Research; the French Ministry of Health; the French Ministry of Labor; French Agency for Food, Environmental and Occupational Health and Safety; French National Research Agency; and the French Institute for Public Health Surveillance. REPRO_PL: This work was supported by the National Centre for Research and Development, Poland (grants PBZ-MEiN-/8/2/2006, K140/P01/2007/1.3.1.1); the Norwegian Financial Mechanism within the PolishNorwegian Research Fund (grant PNRF-218-AI-1/07); and European Community’s Seventh Framework Programme (grant FP7/2007-2013, 603946). Rhea: This work was supported by the European Union Integrated Project NewGeneris, 6th Framework Programme, (grant FOOD-CT-2005-016320); and the Health Impacts of Long-term Exposure to Disinfection By-products in Drinking Water project (grant Food-CT-2006-036224).