[1] Univ Tromso, Fac Hlth Sci, Dept Clin Med, Womens Hlth & Perinatol Res Grp, Tromso, Norway
[2] Univ Hosp North Norway, Dept Clin Res, Tromso, Norway
[3] Univ Hosp North Norway, Dept Surg, Narvik, Norway
[4] Rigshosp, Copenhagen Univ Hosp, Juliane Marie Ctr Women Children & Reprod, Res Unit,Womens & Childrens Hlth, DK-2100 Copenhagen, Denmark
[5] Univ Copenhagen, Inst Clin Med, Fac Hlth & Med Sci, Copenhagen, Denmark
[6] Univ Hosp North Norway, Dept Obstet & Gynecol, Tromso, Norway
[7] Univ Gothenburg, Dept Hlth & Caring Sci, Gothenburg, Sweden
[8] Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden