[1] Natl Inst Hlth & Welf, Dept Chron Dis Prevent, Oulu 90101, Finland
[2] Univ Oulu, Inst Hlth Sci, Oulu, Finland
[3] Oulu Univ Hosp, Dept Pediat & Adolescence, PEDEGO Res Grp, Oulu, Finland
[4] Oulu Univ Hosp, Med Res Ctr Oulu, Dept Obstet & Gynecol, Oulu, Finland
[5] Univ Oulu, Oulu, Finland
[6] Natl Inst Hlth & Welf, Dept Children Young People & Families, Oulu, Finland
[7] Univ Helsinki, Childrens Hosp, Helsinki, Finland
[8] Helsinki Univ Cent Hosp, Helsinki, Finland
[9] Natl Inst Hlth & Welf, Dept Chron Dis Prevent, Helsinki, Finland
[10] Oulu Univ Hosp, NordLab Oulu, Oulu, Finland
[11] Univ Oulu, Dept Clin Chem, Oulu, Finland
[12] Univ Helsinki, Dept Gen Practice & Primary Hlth Care, Helsinki, Finland
[13] Univ Helsinki, Cent Hosp, Unit Gen Practice, Helsinki, Finland
[14] Folkhalsan Res Ctr, Helsinki, Finland
[15] Univ London Imperial Coll Sci Technol & Med, Med Res Ctr Hlth Protect Agcy, Ctr Environm & Hlth, Dept Epidemiol & Biostat,Sch Publ Hlth, London SW7 2AZ, England
[16] Univ Oulu, Bioctr Oulu, Oulu, Finland
[17] Oulu Univ Hosp, Unit Primary Care, Oulu, Finland