1. Department of Obstetrics and Gynecology, University of Essen, Hufelandstr. 55, D‐45122 Essen, Germany
2. Department of Obstetrics and Gynecology, Ludwig‐Maximilians‐University, Marchioninistr. 15, D‐81377 Munich, Germany
3. Department of Medical Informatics, Biometry and Epidemiology (IBE), Ludwig‐Maximilians‐University, Marchioninistr. 15, D‐81377 Munich, Germany