1 Norwegian Research Centre for Women's Health, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Postboks 4956 Nydalen, 0424 Oslo, Norway. Electronic address: [email protected].
2 Laurea University of Applied Sciences, Ratatie 22, 01300 Vantaa, Finland.
3 Department of Obstetrics, Oslo University Hospital, Postboks 4956 Nydalen, 0424 Oslo, Norway.
4 Department of Obstetrics, Haukeland University Hospital, Pb 1400, 5021 Bergen, Norway.