[1] Univ Helsinki, Dept Psychol, FI-00014 Helsinki, Finland
[2] Natl Publ Hlth Inst, Helsinki, Finland
[3] Univ Southampton, MRC, Epidemiol Resource Ctr, Southampton, Hants, England
[4] Univ Southampton, Dev Origins Hlth & Dis Div, Southampton, Hants, England
[5] Univ Helsinki, Dept Gen Practice & Primary Hlth Care, Helsinki, Finland