1. Department of Community and Family Medicine, Duke University Medical Center, Durham, North Carolina.
2. Duke-NUS Graduate Medical School, Singapore.
3. Department of Nutrition, University of North Carolina at Greensboro, Greensboro, North Carolina.
4. Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, North Carolina.
5. Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina.