[1] Univ Copenhagen, Fac Hlth & Med Sci, Sect Epidemiol, Oster Farimagsgade 5A,Box 2099, DK-1014 Copenhagen K, Denmark
[2] Holbaek Cent Hosp, Dept Gynecol & Obstet, Smedelundsgade 60, DK-4300 Holbaek, Denmark
[3] Univ Copenhagen, Fac Hlth & Med Sci, Sect Biostat, Oster Farimagsgade 5 Opg B,POB 2099, DK-1014 Copenhagen K, Denmark