1. Department of Reproductive Medicine and Gynaecology, University Medical Centre Utrecht, Utrecht University, PO Box 85500, 3508 GA Utrecht, The Netherlands
2. Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht University, PO Box 85500, 3508 GA Utrecht, The Netherlands
3. Department of Obstetrics and Gynaecology, St. Antonius Hospital, PO box 2500, 3430 EM Nieuwegein, The Netherlands
4. Department of Obstetrics, Gynaecology and Reproductive Medicine, Noordwest Ziekenhuisgroep, PO Box 750, 1780 AT Den Helder, The Netherlands
5. Department of Gynaecology, St. Franciscus Gasthuis, PO Box 10900, 3004 BA Rotterdam, The Netherlands
6. Fertility Clinic Reinier de Graaf group, Diaconessenhuis Voorburg, PO Box 998, 2275 CX, Voorburg, The Netherlands
7. Department of Obstetrics and Gynaecology, Meander Medical Centre, PO Box 1502, 3800 BM Amersfoort, The Netherlands
8. Centre for Reproductive Medicine, Elisabeth-TweeSteden Hospital, PO Box 90151, 5000 LC Tilburg, The Netherlands
9. Department of Obstetrics and Gynaecology, Onze Lieve Vrouwe Gasthuis West, PO Box 9243, 1006 AE Amsterdam, The Netherlands
10. Department of Gynaecology, Tergooi Hospital, PO Box 1201 DA Blaricum, The Netherlands
11. Department of Epidemiology, University of Groningen, University Medical Centre Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands
12. Centre for Reproductive Medicine, VU University Medical Centre, PO Box 7057, 1007 MB Amsterdam, The Netherlands
13. The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, SA 5006 Adelaide, Australia
14. The South Australian Health and Medical Research Unit, PO Box 11060, SA 5001 Adelaide, Australia