1. Department of Obstetrics and Gynecology Chris Hani Baragwanath Academic Hospital Johannesburg South Africa
2. Faculty of Health Sciences University of the Witwatersrand Johannesburg South Africa
3. Wits Reproductive Health and HIV Institute Faculty of Health Sciences University of the Witwatersrand Johannesburg South Africa
4. London School of Hygiene and Tropical Medicine London UK
5. Department of Obstetrics and Gynecology Charlotte Maxeke Johannesburg Academic Hospital Johannesburg South Africa