1. Department of Public Health, University of Turku, Turku, Finland
2. Research Services, Turku University Hospital, Turku, Finland
3. Department of Public Health, University of Helsinki, Helsinki, Finland
4. Department of Obstetrics and Gynaecology, University of Turku, Turku, Finland
5. Department of Obstetrics and Gynaecology, Turku University Hospital, Turku, Finland