1. Obst Gyn, Prenatal Medicine Erfurt, Erfurt, Germany
2. Leipzig, Center of Prenatal Medicine, Leipzig, Germany
3. Department of Obstetrics and Prenatal Medicine, University Hospital Bonn, Bonn, Germany
4. Obst Gyn, Prenatal Diagnosis and Human Genetics, Berlin, Germany
5. Prenatal Medicine, University Hospital Tuebingen, Tübingen, Germany
6. Prenatal Medicine and Human Genetics, praenatal.de, Duesseldorf, Germany
7. Ultrasound, Prenatal Medicine Munich, Muenchen, Germany