1. Department of PathologyJohns Hopkins University School of Medicine Baltimore Maryland
2. Department of Obstetrics and GynecologyChris Hani Baragwanath Hospital Soweto South Africa
3. Department of Obstetrics and GynecologyKing Edward Hospital Durban South Africa
4. South African National Blood Service Johannesburg South Africa
5. South African Bone Marrow Registry Cape Town South Africa
6. Cryo‐Save Pretoria South Africa
7. Department of Obstetrics and GynecologyMowbray Maternity Hospital Cape Town South Africa
8. Department of Obstetrics and GynecologyGroote Schuur Hospital Cape Town South Africa
9. RTI International Rockville Maryland
10. Kaiser Permanente Northern California Division of Research Oakland California
11. Vitalant Research Institute San Francisco California
12. Department of Laboratory MedicineUniversity of California San Francisco San Francisco California
13. Department of Epidemiology & BiostatisticsUniversity of California San Francisco San Francisco California