1. The Royal Wolverhampton Hospitals NHS Trust; Department of Obstetrics and Gynaecology; New Cross Hospital Wednesfield Wolverhampton West Midlands UK WV10 0QP
2. Nottingham Health Science Partners; Nottingham Clinical Trials Unit; C Floor, South Block Queen's Medical Centre Nottingham UK NG7 2UH
3. University of Nottingham; Department of Obstetrics and Gynaecology; Nottingham City Hospital NHS Trust Hucknall Road Nottingham Nottinghamshire UK NG5 1PB
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