The Copenhagen County child cohort: design of a longitudinal study of child mental health.

Background: Epidemiological studies of psychopathology in the first years of life are few, and the association between mental health problems in infancy and psychiatric disturbances later in life has not been systematically investigated. The aim of the present project was to study mental health problems and possibilities of intervention from infancy and onward.

Methods: The basic study population consists of a birth cohort of 6,090 children born in the year 2000 in the County of Copenhagen, the Copenhagen County Child Cohort, CCCC 2000.