[1] Karolinska Institutet,Division of Obstetrics and Gynecology, Department of Clinical Sciences
[2] Danderyd Hospital,Department of Medical Epidemiology and Biostatistics
[3] Karolinska Institutet,Helsinki University Central Hospital, Department of Obstetrics and Gynecology
[4] Jorvi Hospital,Department of Obstetrics and Gynaecology, Akershus University Hospital
[5] University of Oslo,Department of Obstetrics and Gynecology
[6] Aarhus University Hospital,undefined