1. Department of Obstetrics and Gynaecology; Martini Hospital; Groningen the Netherlands
2. Department of Obstetrics and Gynaecology; Ziekenhuisgroep Twente; Almelo the Netherlands
3. Department of Obstetrics and Gynaecology; Academic Medical Centre; University of Amsterdam; Amsterdam the Netherlands
4. Department of Gynaecology and Reproductive Medicine; University Medical Centre Utrecht; Utrecht the Netherlands