[1] Norwegian Univ Sci & Technol, Dept Publ Hlth & Gen Practice, Trondheim, Norway
[2] Univ Trondheim Hosp, St Olavs Hosp, Dept Obstet & Gynecol, Trondheim, Norway
[3] Norwegian Univ Sci & Technol, Dept Lab Med Childrens & Womens Hlth, Trondheim, Norway
[4] Univ Trondheim Hosp, St Olavs Hosp, Dept Pathol & Med Genet, Trondheim, Norway