Christoph Lees is Reader in Obstetrics and Fetal Medicine at Imperial College London; Honorary Consultant in Obstetrics and Head of Fetal Medicine at Imperial College Healthcare NHS Trust and Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London. Gerard H. A. Visser is Emeritus Professor of Obstetrics, Department of Obstetrics and Gynaecology, University of Utrecht Medical Centre, The Netherlands. Kurt Hecher is Professor and Head, Department of Obstetrics and Fetal Medicine, University Medical Centre, Hamburg, Germany. A previous President of the International Society of Ultrasound in Obstetrics and Gynecology, Hecher is also Deputy Editor-in-Chief of Ultrasound in Obstetrics and Gynecology.