1. University of Copenhagen; Department of Obstetrics; Blegdamsvej 9 Copenhagen Denmark 2100
2. Rigshospitalet, Copenhagen University; Section for Transfusion Medicine, Capital Region Bloodbank; Blegdamsvej 9 Copenhagen Denmark DK 2100
3. Rigshospitalet; The Nordic Cochrane Centre; Blegdamsvej 9, 7811 Copenhagen Denmark 2100
4. Rigshospitalet, Copenhagen University; Department of Obstetrics; Blegdamsvej 9 Copenhagen Denmark DK 2100