1 Division of Obstetrics and Gynecology, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway.
2 Division of Obstetrics and Gynecology, Oslo University Hospital, Oslo, Norway.
3 Department of Pathology, Oslo University Hospital, Oslo, Norway.
4 Division of Obstetrics and Gynecology, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway. Electronic address: uxnnaf@ous-hf.no.