Affiliation: | (1) Department of Obstetrics and Gynaecology, Karolinska Institutet, S?dersjukhuset, Stockholm, Sweden;(2) Department of Clinical Science and Education, Karolinska Institutet, S?dersjukhuset, Stockholm, Sweden;(3) Statisticon AB, Uppsala, Sweden;(4) Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;(5) Kvinnokliniken, S?dersjukhuset, 118 83 Stockholm, Sweden |