1. Department of Obstetrics and Gynaecology; Queens Hospital; Romford; RM7 0AG; UK
2. Department of Obstetrics and Gynaecology; Kings College Hospital; Denmark Hill; Greater London; SE5 9RS; UK
3. Department of Obstetrics and Gynaecology; Whittington Hospital; Magdala Avenue; London; N195NF; UK
4. Bradford Royal Infirmary; Duckworth Lane; Bradford; BD9 6RJ; UK