1. From the Departments of Epidemiology (APS, ALS, CSH, and DD) and Biostatistics and Informatics (JTB and DHG), Colorado School of Public Health, Aurora, CO; the Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora, CO (AML); and the Departments of Epidemiology and Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC