Prevalence of behaviour disorders in low birthweight infants.

OBJECTIVE: To determine the prevalence of behaviour disorders in low birthweight infants. DESIGN: Children of birth weight < or = 2000 g born to mothers resident in Merseyside in 1980-1 assessed using the Rutter parent and teacher behaviour questionnaires and the Conner modification of the Rutter teacher questionnaire. Children attending normal schools were assessed with controls matched for age, sex, and class in school. Children attending special schools were assessed unmatched. SUBJECTS: 233 matched case-control pairs attending normal primary schools and 46 unmatched children attending special schools. SETTING: Primary and special schools. MAIN OUTCOME MEASURES: Emotional, conduct, and undifferentiated behaviour disorders and hyperactivity. RESULTS: On the parental questionnaire screen, 36% of the cases and 22% of the controls had a behaviour disorder and on the teacher questionnaire the proportions were 27% and 12% respectively. Hyperactivity was significantly more common among male cases than their controls (21% v 5.0%) but differed little among female cases and controls (9% v 7%). CONCLUSIONS: Improving neonatal survival of low birthweight infants is accompanied by a higher prevalence of behaviour disorders. The long term implications for psychiatric morbidity and other adult disease must be monitored.