1. Department of Obstetrics and Gynecology, OLVG Amsterdam The Netherlands
2. Perined Utrecht The Netherlands
3. Department of Obstetrics and GynecologyAcademic Medical Center Amsterdam The Netherlands
4. Department of EpidemiologyUniversity of Groningen, University Medical Center Groningen Groningen The Netherlands
5. Department of Obstetrics and GynecologyIsala Klinieken Zwolle The Netherlands
6. Department of Obstetrics and GynecologyMonash University Melbourne Australia