1. Nursing Care Research Centre, Iran University of Medical Sciences, Tehran, Iran
2. Department of Midwifery Science, Amsterdam Public Health Research Institute, VU University Medical Center, Amsterdam, The Netherlands
3. Department of General Practice & Elderly Medicine, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
4. AVAG (Amsterdam/Groningen Midwifery Academy), Groningen, The Netherlands