1. Fetal Medicine UnitJohn Radcliffe Hospital Oxford UK
2. Nuffield Department of Obstetrics and GynaecologyUniversity of Oxford Oxford UK
3. Department of Obstetrics and Gynecology, CHR CitadelleUniversity of Liege Liege Belgium
4. Departments of Pathology and Obstetrics & GynecologyOregon Health & Science University Oregon USA
5. EGA Institute for Women's Health, Faculty of Population Health SciencesUniversity College London London UK