Longitudinal study of behaviour disorders in low birthweight infants

Abstract

Aim - To compare the prevalence of childhood and adolescent behavioural problems in low birthweight infants with matched controls. Methods - A cohort study of a geographically defined population of survivors of ≤ 1500 g birthweight born in 1980 and 1981 and age, sex, and school matched controls was undertaken. Children with a clinical disability were excluded. Data from Rutter questionnaires, completed by parents and teachers when the children were aged 8 and again at age 14 years, were assessed. Results - From an initial 40 321 births in 1980-81 there were 399 of birthweight ≤1500 g, of whom 219 survived to age 8. After exclusion of the 42 children with clinical disability, 177 cases comprised the sample. Of these, 10 (6%) refused or could not be contacted, leaving 167 cases for each of whom a matched control was obtained. At age 14 years, both parent and teacher questionnaires showed an increased prevalence of behavioural problems in cases compared with controls. The presence of a pervasive behavioural problem, when the responses of parents and teachers were concordant, was present in 9% of cases and 3% of controls. There were 132 pairs where the cases and controls were the same at ages 8 and 14 years and provided longitudinal data. The parental questionnaire showed there was a significant decrease in the prevalence of behavioural problems for cases and controls between the ages of 8 and 14 years. There was almost no longitudinal change in the prevalence of behavioural problems as shown by the teacher questionnaires. Conclusion - Although low birthweight infants are at increased risk of behavioural problems, because they comprise only a small proportion of all births, their population attributable risk for behavioural disorder is around 2-3%.