1. Department of Obstetrics and Gynecology, Academic Medical Centre, Amsterdam, The Netherlands
2. Department of Clinical Chemistry and Hematology, University Medical Centre Utrecht, The Netherlands
3. Department of Obstetrics and Gynecology, Catharina Hospital, Eindhoven, The Netherlands
4. Department of Obstetrics and Gynecology, University Medical Centre Utrecht, Utrecht, The Netherlands
5. Department of Obstetrics and Gynecology, Máxima Medical Centre, Veldhoven, The Netherlands
6. Department of Obstetrics and Gynecology, University Hospital Maastricht, Maastricht, The Netherlands
7. Department of Obstetrics, Leiden University Medical Centre, Leiden, The Netherlands
8. Department of Obstetrics and Gynecology, Radboud University Medical Centre, Nijmegen, The Netherlands
9. Department of Obstetrics and Gynecology, VU University Medical Centre, Amsterdam, The Netherlands
10. Department of Obstetrics and Gynecology, Erasmus Medical Centre, Rotterdam, The Netherlands
11. Department of Obstetrics and Gynecology, Isala Clinics, Zwolle, The Netherlands
12. Department of Obstetrics and Gynecology, University Medical Centre Groningen, Groningen, The Netherlands
13. Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, Amsterdam, The Netherlands
14. The Robinson Research Institute School of Medicine, University of Adelaide and The South Australian Health and Medical Research Institute Adelaide Australia, Adelaide, SA, Australia