1. TwinsTrust Centre for Research and Clinical Excellence, St George's University Hospitals NHS Foundation Trust University of London London UK
2. Vascular Biology Research Centre, Molecular and Clinical Sciences Research Institute St George's University of London London UK
3. Fetal Medicine Unit, St George's University Hospitals NHS Foundation Trust University of London London UK
4. Twins Trust Aldershot UK
5. Division of Fetal Medicine, Department of Obstetrics Leiden University Medical Centre Leiden The Netherlands