1. Department of Obstetrics and Gynecology; VU University Medical Center; Amsterdam The Netherlands
2. Department of Obstetrics and Gynecology; University Hospital Sao João; Porto Portugal
3. Department of Anatomy, Embryology & Physiology; Academic Medical Center; Amsterdam The Netherlands
4. Department of Obstetrics and Gynecology; University Medical Center Utrecht; Utrecht The Netherlands
5. Department of Obstetrics; Leiden University Medical Center; Leiden The Netherlands