[1] Univ Southern Denmark, Fac Hlth Sci, Dept Publ Hlth, Res Unit Gen Practice, JB Winslows Vej 9B, DK-5000 Odense, Denmark
[2] Univ Hosp Zealand, Dept Gynecol & Obstet, Roskilde, Denmark
[3] Univ Witwatersrand, Sch Publ Hlth, Johannesburg, South Africa
[4] Brown Univ, IBES, Providence, RI 02912 USA
[5] Karolinska Univ Hosp, Dept Obstet & Gynaecol, Stockholm, Sweden
[6] Univ Southern Denmark, Fac Hlth Sci, Dept Clin Res, RUGO, Odense C, Denmark
[7] Univ Hosp Odense, Dept Gynaecol & Obstet, Odense C, Denmark