1. Division of Anatomical Pathology, Faculty of Medicine and Health Sciences, Tygerberg Hospital, National Health Laboratory Service, Stellenbosch University, Cape Town, South Africa
2. Department of Obstetrics and Gynecology, Tygerberg Hospital, Cape Town, South Africa
3. Department of Obstetrics and Gynecology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
4. Department of Obstetrics and Gynecology, Paarl Hospital, Cape Town, South Africa
5. Lancet Laboratories, Johannesburg, South Africa
6. Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa