1. Tameside Hospital NHS Foundation Trust; Fountain Street Ashton-under-Lyne UK OL6 9RW
2. The University of Manchester; Division of Nursing Midwifery and Social Work; Jean McFarlane Building Oxford Road Manchester UK M13 9PL
3. Women's and Children's Hospital; Department of Women's Anaesthesia; 72 King William Road Adelaide South Australia Australia 5006
4. The University of Liverpool; Cochrane Pregnancy and Childbirth Group, Department of Women's and Children's Health; First Floor, Liverpool Women's NHS Foundation Trust Crown Street Liverpool UK L8 7SS