1. Department of Family Medicine, University of KwaZulu-Natal, Durban, South Africa;
2. Umlazi CRS, Centre for AIDS Programme of Research in South Africa, Durban, South Africa;
3. Department of Obstetrics and Gynaecology, University of KwaZulu-Natal, Durban, South Africa; and
4. Center for Biostatistics in AIDS Research, Harvard T.H. Chan School of Public Health, Boston, MA.