1. Department of Obstetrics and Gynecology, City Hospital of Aschaffenburg, Aschaffenburg, Germany
2. Department of Obstetrics and Gynecology, Health and Care Center Ruesselsheim, Ruesselsheim, Germany
3. Institute for Medical Biometry, Epidemiology and Informatics, University of Mainz, Mainz, Germany
4. Institute for Transfusion Medicine, Charité Humboldt-University, Berlin, Germany