[1] Linkoping Univ, Div Drug Res Anaesthesiol & Intens Care, Dept Med & Hlth Sci, Linkoping, Sweden
[2] Cty Council Ostergotland, Dept Anaesthesia & Intens Care, Linkoping, Sweden
[3] Linkoping Univ, Fac Hlth Sci, Div Obstet & Gynaecol, Dept Clin & Expt Med, Linkoping, Sweden
[4] Cty Council Ostergotland, Dept Obstet & Gynaecol, S-58185 Linkoping, Sweden