1. Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
2. Department of Obstetrics and Gynecology, Seinäjoki Central Hospital, Seinäjoki, Finland
3. Faculty of Social Sciences, Tampere University, Tampere, Finland
4. Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland
5. Department of Obstetrics and Gynecology, University of Oulu and Oulu University Hospital, Medical Research Center, PEDEGO Research Unit, Oulu, Finland