1. a Department of Psychology , University of Pretoria , Pretoria , South Africa
2. b Center for Interdisciplinary Research on AIDS , Yale University , New Haven , United States
3. c Serithi project , University of Pretoria , Pretoria , South Africa
4. d Department of Obstetrics and Gynaecology , University of Pretoria , Pretoria , South Africa
5. e Maternal and Infant Health Care Strategies , Medical Research Council , South Africa