1. Department of Obstetrics and Gynaecology; Academic Medical Centre; Amsterdam The Netherlands
2. Department of Clinical Epidemiology; Biostatistics and Bioinformatics, Academic Medical Centre; Amsterdam The Netherlands
3. Department of Obstetrics and Gynaecology; Atrium Medical Centre; Heerlen The Netherlands
4. Julius Centre for Health Sciences and Primary Care; University Medical Centre Utrecht; Utrecht The Netherlands
5. Department of Obstetrics and Gynaecology; Leiden University Medical Centre; Leiden The Netherlands
6. Department of Obstetrics and Gynaecology; Erasmus Medical Centre; Rotterdam The Netherlands
7. Department of Obstetrics and Gynaecology; Isala Clinics; Zwolle The Netherlands
8. Department of Obstetrics and Gynaecology; University Medical Centre Groningen; Groningen The Netherlands
9. Department of Obstetrics and Gynaecology; University Medical Center Utrecht; Utrecht The Netherlands
10. Department of Obstetrics and Gynaecology; Maastricht University Medical Center; Maastricht The Netherlands
11. Department of Obstetrics and Gynaecology; ZGT; Almelo The Netherlands
12. Department of Obstetrics and Gynaecology; Radboud University Nijmegen; Nijmegen The Netherlands
13. The Robinson Institute, School of Paediatrics and Reproductive Health; University of Adelaide; Adelaide Australia
14. Department of Obstetrics and Gynaecology; Onze Lieve Vrouwe Gasthuis; Amsterdam The Netherlands
15. Department of Public Health; Academic Medical Centre; Amsterdam The Netherlands