1. Department of Obstetrics and Gynecology, University of Turku, Turku, Finland
2. Department of Health Promotion, Metropolia University of Applied Sciences, Helsinki, Finland
3. Department of Obstetrics and Gynecology, Turku University Hospital and University of Turku, Turku, Finland
4. Department of Clinical Medicine, Biostatistics, University of Turku, Turku, Finland