[1] Gothenburg Univ, Sahlgrenska Univ Hosp, Sahlgrenska Acad, Dept Obstet & Gynecol, Gothenburg, Sweden
[2] UiT Arctic Univ Norway, Fac Hlth Sci, Dept Community Med, Res Grp Epidemiol Chron Dis, Tromso, Norway
[3] Karolinska Insitute, Dept Womens & Childrens Hlth, Div Obstet & Gynecol, Stockholm, Sweden
[4] Karolinska Univ Hosp, Stockholm, Sweden
[5] Univ Helsinki, Dept Obstet & Gynecol, Helsinki, Finland
[6] Helsinki Univ Hosp, Helsinki, Finland
[7] Univ Copenhagen, Univ Hosp, Rigshosp, Dept Obstet & Gynecol,Fac Hlth Sci, Copenhagen, Denmark