1. Department of Midwifery Science, AVAG/Amsterdam Reproduction and Development Center Amsterdam University Medical Centres, Vrije Universiteit Amsterdam Amsterdam Netherlands
2. Department of Midwifery, School of Health Sciences University of Nottingham Nottingham UK
3. Department of Obstetrics and Gynaecology Maxima Medical Centre Veldhoven the Netherlands
4. Department of Obstetrics and Gynaecology, Amsterdam Reproduction and Development Center Amsterdam University Medical Centre, Universiteit van Amsterdam Amsterdam the Netherlands
5. Research Centre for Midwifery Science Zuyd University Maastricht the Netherlands
6. CAPHRI School for Public Health and Primary Care Maastricht University Maastricht the Netherlands
7. Department of Midwifery Science, AVAG/Amsterdam Public Health Research Institute Amsterdam University Medical Centres, Vrije Universiteit Amsterdam Amsterdam Netherlands
8. Department of General Practice and Elderly Care Medicine University of Groningen, University Medical Centre Groningen Groningen the Netherlands