1. Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, UK
2. Public Health Department, Faculty of Medicine and Health Sciences, An-Najah National University, Rafidia Street, PO Box 7, Nablus, Palestine
3. Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland
4. Population Health Sciences, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol BS8 2PS, UK