1. South African Medical Research Council/University of Pretoria Maternal and Infant Health Care Strategies Unit, Department of Obstetrics and Gynaecology, University of Pretoria, Unit Private Bag X323 Arcadia, Pretoria0007, South Africa.
2. Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, United States of America.
3. Department of Sexual and Reproductive Health and Research, World Health Organization, Geneva, Switzerland.