The Scottish low birthweight study: II. Language attainment, cognitive status, and behavioural problems.
Of the 636 survivors of a total geographically based population born in Scotland in 1984, who weighed less than 1750 g at birth, 611 (96%) were assessed at 4.5 years to determine the prevalence of language, cognitive, and behavioural problems. Language development was significantly related to birth weight, gestational age, and social class for comprehension, less so for expressive language. Mean (SD) intelligence quotient (IQ) on the British ability scales was 92.9 (14.7). Within this population there were no significant differences between birthweight groups. Overall they performed poorly on visual recognition, verbal comprehension and number skills subscales--in the latter those with birth weights less than 1000 g were significantly worse than the heavier children. Only 5% had IQs less than 70, but a further 3% could not be tested because of other physical disability. Among those with normal IQs were groups of children who exhibited patterns of skill deficits in different subscales raising the possibility of specific learning difficulties. Poor attention span was reported in 47%, and parents said the study children had more behavioural problems than their siblings.