Behavioural problems in children who weigh 1000 g or less at birth in fourcountries

Background The increased survival chances of extremely low-birthweight (ELB W) infants (weighing less than or equal to 1000 g at birth) has led to conc ern about their behavioural outcome in childhood. In reports from several c ountries with different assessments at various ages, investigators have not ed a higher frequency of behavioural problems in such infants, but cross-cu ltural comparisons are lacking. Our aim was to compare behavioural problems in ELBW children of similar ages from four countries. Methods We prospectively studied 408 ELBW children aged 8-10 years, whose p arents completed the child behaviour checklist. The children came from the Netherlands. Germany, Canada, and USA. The checklist provides a total probl em score consisting of eight narrow-band scales. Of these, two (aggressive and delinquent behaviour) give a broad-band externalising score, three (anx ious, somatic, and withdrawn behaviour) give a broad-band internalising sco re, and three (social, thought, and attention problems) indicate difficulti es fitting neither broad-band dimension. For each cohort we analysed scores in ELBW children and those in normal-birthweight controls (two cohorts) or national normative controls (two cohorts). Across countries, we assessed d eviations of the ELBW children from normative or control groups. Findings ELBW children had higher total problem scores than normative or co ntrol children, but this increase was only significant in European countrie s. Narrow-band scores were raised only for the social, thought, and attenti on difficulty scales, which were 0.5-1.2 SD higher in ELBW children than in others. Except for the increase in internalising scores recorded for one c ohort, ELBW children did not differ from normative or control children on i nternalising or externalising scales. Interpretation Despite cultural differences, types of behavioural problems seen in ELBW children were very similar in the four countries. This finding suggests that biological mechanisms contribute to behavioural problems of ELBW children.