Children of low birthweight in the 1946 national cohort. Behaviour and educational achievement in adolescence.

Among 12 468 legitimate single births in the first week of March 1946, 163 weighed 200 g or less (LBW group) and of these 80 survived to 18 years. 6 of the LBW survivors emigrated with their families and 5 have not been traced since birth. The remaining 69 were followed up to the age of 15 at which time two early school leavers were lost to the study. There is evidence that none of the survivors who emigrated or left the sample and serious physical or mental impairment. Compared with individually matched controls, the LBW children showed similar proportions with severe physical, mental, or behavioural handicaps. There are small and statistically nonsignificant differences in favour of the controls in ability and attainment scores at 15 years and in the level of academic qualifications gained by the age of 18. If the mean ability and attainment scores are expressed as an "intelligence quotient" with a mean of 100 and a standard deviation of 15, the LBW group has an average IQ of 93 and the controls of 97. Hospital stay after childbirth was much longer in 1946 than today and many LBW children spent more than 3 weeks in hospital. There is no evidence that long hospital stay was associated with problems of behaviour or learning in adolescence.