1. Department of Obstetrics and Gynaecology, GPR Clinical Centre Ruesselsheim
2. Department of Obstetrics and Gynaecology, University of Saarland
3. Department of Obstetrics and Gynaecology, Georg-August-University of Goettingen
4. Department of Obstetrics and Gynaecology, Medical University of Vienna
5. Department of Obstetrics and Gynaecology, University of Duisburg-Essen
6. Department of Obstetrics and Gynaecology, Cologne University