1. Department of Obstetrics and Gynaecology; Academic Medical Centre; Amsterdam the Netherlands
2. Department of Midwifery Science; AVAG/EMGO Institute for Health and Care Research; VU University Medical Centre; Amsterdam the Netherlands
3. Maxima Medical Centre; Veldhoven the Netherlands
4. Department of Obstetrics and Gynaecology; Leiden University Medical Centre; Leiden the Netherlands
5. Department of Obstetrics and Gynaecology; Onze Lieve Vrouwe Gasthuis; Amsterdam the Netherlands
6. Department of Anesthesiology; Onze Lieve Vrouwe Gasthuis; Amsterdam the Netherlands
7. Department of Obstetrics and Gynaecology; St Antonius Hospital; Nieuwegein the Netherlands
8. Department of Anaesthesiology; St Antonius Hospital; Nieuwegein the Netherlands
9. Department of Obstetrics and Gynaecology; Diakonessen Hospital; Utrecht the Netherlands
10. Department of Anaesthesiology; Diakonessen Hospital; Utrecht the Netherlands
11. Midwifery Practice Alnatal; Nieuwegein the Netherlands
12. The Robinson Research Institute School of Medicine; University of Adelaide and The South Australian Health and Medical Research Institute Adelaide Australia; Adelaide SA Australia