1. Carolina Population Center, University of North Carolina, Chapel Hill, NC, USA
2. Department of Public Policy, University of North Carolina, Chapel Hill, NC, USA
3. UNICEF Office of Research, Florence, Italy
4. Harvard Center for Population and Development Studies, Harvard University, Cambridge, MA, USA
5. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
6. Department of Maternal & Child Health, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
7. Department of Health Policy & Management, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA