1. Department of Obstetrics and Gynaecology Whipps Cross University Hospital Barts Health Trust London UK
2. Department of Obstetrics and Gynaecology Homerton University Hospital London UK
3. Department of Obstetrics and Gynaecology North Middlesex University Hospital London UK
4. Department of Obstetrics and Gynaecology Royal London Hospital Barts Health NHS Trust London UK
5. Department of Obstetrics and Gynaecology Newham Hospital Barts Health NHS Trust London UK
6. Statsconsultancy Ltd Amersham Buckinghamshire UK