1. Department of Pathology; Johns Hopkins University School of Medicine; Baltimore Maryland
2. Blood Systems Research Institute; San Francisco California
3. South African National Blood Service; Johannesburg South Africa
4. South African Bone Marrow Registry; Cape Town South Africa
5. Department of Obstetrics and Gynecology; Chris Hani Baragwanath Hospital; Soweto South Africa
6. Department of Obstetrics and Gynecology; Mowbray Maternity Hospital
7. Department of Obstetrics and Gynecology; Groote Schuur Hospital; Cape Town South Africa
8. Department of Obstetrics and Gynecology; King Edward Hospital; Durban South Africa
9. Cryo-Save; Pretoria South Africa
10. RTI international; Rockville Maryland
11. Western Province Blood Transfusion Service; Cape Town South Africa
12. Departments of Laboratory Medicine and Epidemiology/Biostatistics; University of California San Francisco; San Francisco California