[1] Linkoping Univ, Dept Clin & Expt Med, Fac Hlth Sci, SE-58183 Linkoping, Sweden
[2] Cty Council Ostergotland, Dept Gynaecol & Obstet Linkoping, Linkoping, Sweden
[3] Uppsala Univ, Dept Womens & Childrens Hlth, Akad Sjukhuset, SE-75185 Uppsala, Sweden
[4] Karolinska Inst, Dept Womens & Childrens Hlth, Tomtebodavagen 18A, SE-17177 Stockholm, Sweden