1. Department of Obstetrics and Gynaecology; University Medical Centre Mannheim; Heidelberg University; Heidelberg Germany
2. Department of Obstetrics and Gynaecology; Erlangen University Hospital; Erlangen Germany
3. Department of Obstetrics; Jena University Hospital; Jena Germany
4. Department of Obstetrics and Gynaecology; Frankenthal Hospital; Frankenthal Germany
5. Department of Obstetrics and Gynaecology; Diakonie Hospital; Mannheim Germany
6. Department of Medical Statistics and Biomathematics; University Medical Centre Mannheim; Heidelberg University; Heidelberg Germany
7. Department of Obstetrics and Gynaecology; Ludmillenstift Hospital; Meppen Germany