1 Department of Obstetrics and Department of Gynecology, Oslo University Hospital, Ullevål and Faculty of Medicine, University of Oslo, Norway.
2 University of Glasgow, School of Medicine, Glasgow, UK.
3 Department of Pathology, Oslo University Hospital, Ullevål and Faculty of Medicine, University of Oslo, Norway.
4 Department of Obstetric Medicine, University of Oxford, Oxford, UK.
5 Department of Obstetrics and Department of Gynecology, Oslo University Hospital, Ullevål and Faculty of Medicine, University of Oslo, Norway. Electronic address: [email protected].