1. Departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston, Massachusetts;
2. Epidemiology Branch, Division of Epidemiology, Statistics, and Prevention Research, Eunice Kennedy Shriver National Institute of Child Health and Development, Bethesda, Maryland;
3. Department of Epidemiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore;
4. Department of Public Health and Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore;