University of Bonn - Department of Obstetrics and Prenatal Medicine, Justus-Liebig-Universität Gießen, University of Cologne, Friedrich-Alexander-Universität Erlangen-Nürnberg, University of Tübingen, Hallerwiese Clinic, Erfurt Prenatal Diagnostic Centre, Vivantes Clinic Neukoeln, University of Leipzig - University Hospital Leipzig, University of Hamburg - Center for Internal Medicine, Charité - Universitätsmedizin Berlin - Department of Obstetrics, St. Josef Hospital, University Hospital of Schleswig-Holstein, University of Bonn - Department of Obstetrics and Prenatal Medicine and University of Bonn - Department of Obstetrics and Prenatal Medicine