1. Department of Epidemiology, Gillings School of Global Public Health University of North Carolina at Chapel Hill Chapel Hill North Carolina USA
2. Department of Epidemiology and Biostatistics, School of Public Health University of Zambia Lusaka Zambia
3. Department of Obstetrics and Gynecology, School of Medicine University of Zambia Lusaka Zambia
4. University of North Carolina Global Projects Zambia Lusaka Zambia
5. Department of Obstetrics and Gynecology, School of Medicine University of North Carolina at Chapel Hill Chapel Hill North Carolina USA