1. Department of Midwifery Science; AVAG and the EMGO Institute for Health and Care Research; VU University Medical Centre; Amsterdam the Netherlands
2. NIVEL (Netherlands Institute for Health Services Research); Utrecht the Netherlands
3. Department of Midwifery Science; EMGO+VUMc; Amsterdam the Netherlands
4. Department of Obstetrics and Gynaecology; University of Groningen; Groningen the Netherlands
5. University Medical Centre Groningen; Groningen the Netherlands
6. Department of Public Health; Rural Health School; La Trobe University; Melbourne Vic. 3086 Australia
7. EMGO+VUMc; Amsterdam the Netherlands
8. Department of Obstetrics and Gynaecology; McMaster University; Hamilton ON Canada