1. Nuffield Department of Obstetrics & Gynaecology; University of Oxford; Oxford UK
2. Bodleian Health Care Libraries; University of Oxford; Oxford UK
3. Maternité Necker-Enfants Malades, AP-HP; Université Paris Descartes; Paris France
4. Fetal Medicine Unit; Department of Obstetrics and Gynaecology, St. George's University Hospitals NHS Foundation Trust, Molecular and Clinical Sciences Research Institute; London UK