1. Department of Obstetrics and Gynaecology, University of Pretoria and Steve Biko Academic Hospital, Pretoria, South Africa
2. South African Medical Research Council Maternal and Infant Health Care Strategies Unit, Department of Obstetrics and Gynaecology, University of Pretoria, Pretoria, South Africa
3. Netcare Waterfall Hospital, Midrand, South Africa
4. Sunninghill Hospital, Sandton, South Africa
5. Singapore Eye Research Institute, Singapore, Singapore