1. Institute for Transfusion Medicine; University Hospital Hamburg-Eppendorf; Hamburg; Germany
2. Department of Haemostaseology; AescuLabor Hamburg; Hamburg; Germany
3. Department of Gynecology and Obstetrics; University Hospital Göttingen; Göttingen; Germany
4. Department of Medical Biometry and Epidemiology; University Hospital Eppendorf; Hamburg; Germany