Imperial College London - Medical Research Council-Health Protection Agency Centre for Environment and Health, Peking University - Institute of Reproductive and Child Health, King’s College London - MRC-PHE Centre for Environment and Health, Chinese Academy for Environmental Planning, Peking University - Center for Healthy Aging and Development Studies, Peking University - Institute of Reproductive and Child Health, Zhejiang University, Peking University and Peking University - College of Environmental Science and Engineering