title: THE AUTHORS REPLY.
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Anne Johanne
authors.initials: AJ
authors.lastname: Søgaard
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.|Department of Community Medicine, Institute of Health and Society, University of Oslo, Oslo, Norway.
authors.forename: Tone K
authors.initials: TK
authors.lastname: Omsland
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Kristin
authors.initials: K
authors.lastname: Holvik
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.|Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors.forename: Grethe S
authors.initials: GS
authors.lastname: Tell
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Cecilie
authors.initials: C
authors.lastname: Dahl
authors.affiliation: Department of Public Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Obstetrics and Gynecology, St. Olav's University Hospital, Trondheim, Norway.
authors.forename: Berit
authors.initials: B
authors.lastname: Schei
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.|Department of Community Medicine, Institute of Health and Society, University of Oslo, Oslo, Norway.
authors.forename: Haakon E
authors.initials: HE
authors.lastname: Meyer