1. Department of Obstetrics and Gynaecology; University of Tuebingen; Tuebingen; Germany
2. Department of Obstetrics and Gynaecology; Klinikum Bad Cannstatt; Stuttgart; Germany
3. Fetal Medicine Foundation USA, Dayton, OH, USA and Division of Maternal Fetal Medicine; Wright State University; Dayton; OH; USA
4. Center for Prenatal Diagnosis and Genetics; Nuremberg; Germany