1. Division of Obstetrics and Gynaecology; Department of Women's and Children's Health; Karolinska Institutet and Karolinska University Hospital; Stockholm Sweden
2. GynMed Clinic; Vienna Austria
3. Department of Obstetrics and Gynaecology; Sahlgrenska Academy at Gothenburg University; Sahlgrenska University Hospital; Gothenburg Sweden
4. Department of Obstetrics and Gynaecology; Norrtälje Hospital; Norrtälje Sweden
5. Statisticon AB; Stockholm Sweden