1. Department of Obstetrics and Gynaecology; Martini Hospital; Groningen The Netherlands
2. Department of Obstetrics and Gynaecology; Academic Medical Center; University of Amsterdam; Amsterdam The Netherlands
3. Department of Obstetrics and Gynaecology; Isala Clinics; Zwolle The Netherlands
4. Department of Urology; Martini Hospital; Groningen The Netherlands
5. Department of Gynaecology and Reproductive Medicine; University Medical Center Utrecht; Utrecht The Netherlands