Affiliation: | (1) Department of Obstetrics and Gynaecology, Oslo University Hospital, Ulleval, 0407 Oslo, Norway;(2) Center for Clinical Research, Oslo University Hospital, Ulleval, Oslo, Norway;(3) Faculty of Medicine, University of Oslo, Oslo, Norway;(4) Department of Obstetrics and Gynecology, Baerum Central Hospital, Akershus, Norway |