1. Institute of Education, University of London; Evidence for Policy and Practice Information and Coordinating Centre (EPPI-Centre), Social Science Research Unit (SSRU); 10 Woburn Square London UK WC1H 0NR
2. Aberdeen Maternity Hospital; Obstetrics and Gynaecology; Foresterhill Aberdeen UK AB9 2ZD
3. Counties Manukau District Health Board; Auckland New Zealand
4. University of Aberdeen, Aberdeen Maternity Hospital; Division of Applied Health Sciences; Aberdeen UK AB9 2ZD