[1] Sunderby Hosp, Dept Obstet & Gynecol, S-97180 Lulea, Sweden
[2] Sunderby Hosp, Dept Internal Med, S-97180 Lulea, Sweden
[3] Umea Univ, Dept Clin Sci Obstet & Gynecol, S-90187 Umea, Sweden
[4] Uppsala Univ, Dept Womens & Childrens Hlth, S-75105 Uppsala, Sweden