1. Department of Obstetrics, Gynecology, Gynecologic Oncology and Senology, Bethesda Hospital Duisburg, 47053 Duisburg, Germany
2. Faculty of Mathematics and Computer Science, University of Bremen, 28359 Bremen, Germany
3. Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90133 Palermo, Italy