1. Department of Gynecology and Obstetrics, University Hospital Schleswig-Holstein, Campus Lübeck, 23538 Lübeck, Germany
2. Department of Gynecology and Obstetrics, Democritus University of Thrace, 68100 Alexandroupolis, Greece
3. Department of Gynecology and Obstetrics, University Hospital Düsseldorf, 40225 Düsseldorf, Germany