1. Department of Obstetrics and Gynecology; Kuopio University Hospital; Kuopio Finland
2. Department of Public Health; University of Helsinki; Helsinki Finland
3. Living Environment and Health Unit, National Institute for Health and Welfare; Kuopio Finland
4. Department of Obstetrics and Gynecology; Helsinki University Hospital; Helsinki Finland
5. Institute of Clinical Medicine, School of Medicine; University of Eastern Finland; Kuopio Finland