1 Department of Obstetrics and Gynaecology, University Hospitals Bristol National Health Service (NHS) Trust, St Michael's Hospital, Southwell St, Bristol, BS2 8EG, United Kingdom. Electronic address: [email protected].
2 Department of Obstetrics and Gynaecology, University Hospitals Bristol NHS Trust, Bristol, United Kingdom; Royal College of Obstetricians and Gynaecologists.
3 Department of Obstetrics and Gynaecology, North Bristol NHS Trust, Bristol, United Kingdom.
4 Department of Obstetrics and Gynaecology, North Bristol NHS Trust, Bristol, United Kingdom; Royal College of Obstetricians and Gynaecologists.