1. Department of Obstetrics and Gynecology, PEDEGO Research Unit, Oulu University Hospital and University of Oulu, 90029 OYS, Finland
2. Medical Research Center Oulu, Oulu University Hospital and University of Oulu, 90014 Oulu, Finland
3. Northern Finland Laboratory Centre Nordlab, 90220 Oulu, Finland
4. Department of Clinical Chemistry, University of Oulu, 90014 Oulu, Finland
5. Department of Chronic Disease Prevention, National Institute for Health and Welfare, 90101 Oulu, Finland