[1] Oslo & Akershus Univ, Coll Appl Sci, Fac Hlth, NO-0130 Oslo, Norway
[2] Univ Hosp North Norway, Dept Radiol, Tromso, Norway
[3] Homebirth Assoc, Region Zealand, Soro, Denmark
[4] Oslo Univ Hosp, Clin Genet Unit, Oslo, Norway
[5] Copenhagen Univ Hosp, Rigshosp, Juliane Marie Ctr Women Children & Reprod, Res Unit,Womens & Childrens Hlth, Copenhagen, Denmark
[6] Univ Iceland, Fac Nursing, Dept Midwifery, Reykjavik, Iceland
[7] Univ Hosp North Norway, Dept Obstet & Gynecol, Tromso, Norway
[8] Univ Tromso, Fac Hlth Sci, Dept Clin Med, Womens Hlth & Perinatol Res Grp, Tromso, Norway
[9] Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden