1. Marienhospital, Bottrop, Germany;
2. Alfred-Krupp-Krankenhaus Essen, Essen, Germany;
3. Department of Obstetrics and Gynecology, University Hospital Essen, Essen, Germany;
4. Department of Gynecology and Obstetrics, Marienhospital Bottrop, Bottrop, Germany;
5. Marienhospital Bottrop gGmbH, Bottrop, Germany;
6. Marienhospital Bottrop, Klinik für Gynäkologie und Geburtshilfe, Bottrop, Germany;
7. Charite-University Medicine Berlin, Berlin, Germany;