1. Department of Obstetrics and Gynaecology; University of Tuebingen; Tuebingen Germany
2. Fetal Medicine Foundation USA; Dayton OH USA
3. Division of Maternal Fetal Medicine; Wright State University; Dayton OH USA
4. Practice for Prenatal Diagnosis; Munich Germany
5. Fetal Medicine Unit, Department of Obstetrics and Gynaecology, University Medical Centre Groningen; University of Groningen; Groningen The Netherlands