1. Department of Obstetrics and Gynecology, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
2. Department of Obstetrics and Gynecology, Turku University Hospital and University of Turku, 20014 Turku, Finland
3. Department of Obstetrics and Gynecology, Vaasa Central Hospital, 65130 Vaasa, Finland
4. SMW Consultants, Ltd., 21620 Kaarina, Finland
5. Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
6. Department of Pathology, Turku University Hospital, 20014 Turku, Finland
7. Department of Oral Pathology and Oral Radiology, Institute of Dentistry, Faculty of Medicine, University of Turku, 20014 Turku, Finland
8. Department of Obstetrics and Gynecology, Tampere University Hospital, 33100 Tampere, Finland