1. Department of Obstetrics and Gynecology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
2. SMW Consultants, Ltd, Kaarina, Finland.
3. Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
4. Department of Obstetrics and Gynecology, Turku University Hospital, University of Turku, Turku, Finland.
5. Department of Oral Pathology, Institute of Dentistry, Faculty of Medicine, University of Turku, Turku, Finland.
6. Department of Obstetrics and Gynecology, Tampere University Hospital, Tampere, Finland.