Outdoor air pollution, preterm birth, and low birth weight: analysis of the World Health Organization global survey on maternal and perinatal health - Fleischer, Nancy L.; Merialdi, Mario; Donkelaar, Aaron van; Vadillo-Ortega, Felipe; Martin, Randall V.; Betran, Ana Pilar; Souza, João Paulo; O'Neill, Marie S. (Environmental Health Perspectives, 2014)