[1] Natl Inst Hlth & Welf, Dept Lifestyle & Participat, Nutr Unit, FI-00271 Helsinki, Finland
[2] Univ Helsinki, Hjelt Inst, Helsinki, Finland
[3] Univ Tampere, Sch Hlth Sci, FIN-33101 Tampere, Finland
[4] Univ Turku, Dept Social Res, Turku, Finland
[5] London Sch Hyg & Trop Med, Dept Epidemiol & Populat Hlth, Med Statist Unit, London WC1, England
[6] Univ Turku, Dept Pediat, Turku, Finland
[7] Univ Oulu, Dept Pediat, SF-90100 Oulu, Finland
[8] Univ Turku, Immunogenet Lab, Turku, Finland
[9] Univ Eastern Finland, Dept Clin Microbiol, Kuopio, Finland
[10] Univ Helsinki, Childrens Hosp, Cent Hosp, Helsinki, Finland
[11] Univ Helsinki, Folkhalsan Res Ctr, Helsinki, Finland
[12] Tampere Univ Hosp, Dept Pediat, Tampere, Finland
[13] Univ Tampere, Ctr Sci, FIN-33101 Tampere, Finland