1 Department for Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Obstetrics and Gynaecology/Multidisciplinary Pain Clinic, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway. Electronic address: cecilie.hagemann@ntnu.no.
2 Department of Pain Management and Research, Oslo University Hospital, Oslo, Norway.