Pre- and perinatal environmental origin in mild mental retardation.

From population-based studies of mild mental retardation made in the beginning of the 1980s in Sweden and covering the birth years 1959-70, data on pre- and perinatal environmental origin have been analysed. Information gathered from these data has also been compiled together with more recent findings from epidemiological studies of other brain impairment groups, in particular cerebral palsy and infantile hydrocephalus.