1. Department of Obstetrics and Gynaecology, University of Tübingen, Tübingen, Germany
2. Prof. Tutschek, Prenatal Zürich, Zürich, Switzerland
3. Centre for Ultrasound and Prenatal Medicine, Frankfurt/Main, Germany
4. Gynäkologie und Geburtshilfe, Praxis für Pränatalmedizin, Weimar, Germany
5. Praxis, Prenatal Diagnosis and Human Genetics, Berlin, Germany
6. Leipzig, Center of Prenatal Medicine, Leipzig, Germany
7. Frauenklinik, Evangelisches Diakoniekrankenhaus, Schwäbisch-Hall, Germany
8. Obstetrics and Gynecology, Praxis für Pränatalmedizin, Erfurt, Germany
9. Department of Prenatal Medicine and Gynecologic Ultrasound, University Hospital Basel, Switzerland
10. Department of Obstetrics and Gynecology, Medical University of Vienna, Austria
11. Department of Obstetrics and Gynecology, Medical University Graz, Austria
12. Department of Obstetrics and Gynecology, University of Ulm, Germany