Longitudinal study of behaviour disorders in low birthweight infants

Aim-To compare the prevalence of childhood and adolescent behavioural probl ems in low birthweight infants with matched controls. Methods-A cohort study of a geographically defined population of survivors of less than or equal to 1500 g birthweight born in 1980 and 1981 and age, sex, and school matched controls was undertaken. Children with a clinical d isability were excluded. Data from Rutter questionnaires, completed by pare nts and teachers when the children were aged 8 and again at age 14 years, w ere assessed. Results-From an initial 40 321 births in 1980-81 there were 399 of birthwei ght less than or equal to 1500 g, of whom 219 survived to age 8. After excl usion of the 42 children with clinical disability, 177 cases comprised the sample. Of these, 10 (6%) refused or could not be contacted, leaving 167 ca ses for each of whom a matched control was obtained. At age 11 years, both parent and teacher questionnaires showed an increased prevalence of behavio ural problems in cases compared with controls. The presence of a pervasive behavioural problem, when the responses of parents and teachers were concor dant, was present in 9% of cases and 3% of controls. There were 132 pairs w here the cases and controls were the same at ages 8 and 14 years and provid ed longitudinal data. The parental questionnaire showed there was a signifi cant decrease in the prevalence of behavioural problems for cases and contr ols between the ages of 8 and 14 years. There was almost no longitudinal ch ange in the prevalence of behavioural problems as shown by the teacher ques tionnaires. Conclusion-Although low birthweight infants are at increased risk of behavi oural problems, because they comprise only a small proportion of all births , their population attributable risk for behavioural disorder is around 2-3 %.