[1] Oulu Univ, Dept Publ Hlth Sci & Gen Practice, Oulu, Finland
[2] Oulu Univ, Clin Child Psychiat, Oulu, Finland
[3] Univ Hosp Oulu, Oulu, Finland
[4] Oulu Univ, Dept Obstet & Gynecol, Oulu, Finland
[5] Univ Calif Los Angeles, Inst Neuropsychiat, Dept Psychiat & Behav Sci, Los Angeles, CA 90024 USA
[6] Univ London Imperial Coll Sci Technol & Med, Dept Epidemiol & Publ Hlth, London SW7 2AZ, England