1. Department of Epidemiology,Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
2. Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
3. FHI 360, Durham, North Carolina, United States
4. Department of Maternal and Child Health, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
5. The Institute of Reproductive Health at Georgetown University, Washington D. C., United States