1. Centre for ultrasound and prenatal medicine, Frankfurt/Main, Germany
2. amedes MVZ für Laboratoriumsmedizin, Göttingen, Germany
3. Amedes experts Barkhof, Germany
4. Institut für Laboratoriumsmedizin und Klinische Genetik, Essen, Germany
5. Centre for prenatal medicine, Leipzig, Germany
6. Ultraschall Freie Strasse Basel, Switzerland
7. FMF Audit Centre Germany, Adelebsen, Germany
8. Department of Medical Biostatistics, Epidemiology and Informatics of the University of Mainz, Mainz, Germany
9. Department of Biostatistics, CIMH Mannheim, Mannheim Medical School of the University of Heidelberg, Mannheim, Germany