1. Nottingham Clinical Trials Unit, University of Nottingham, Nottingham, UK
2. Birmingham Clinical Trials Unit, University of Birmingham, Birmingham, UK
3. Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
4. Department of Obstetrics and Gynaecology, Whipps Cross Hospital, London, UK
5. Department of Gynaecology, St George’s Hospital and Medical School, London, UK
6. Department of Radiology, St George’s Hospital and Medical School, London, UK
7. School of Medicine, University of Glasgow, Glasgow, UK
8. Department of Primary Care, University of Oxford, Oxford, UK