Some influences on cognitive development in a group of very low birthweight infants at four years

To report the findings of an audit of 91 < 1,500 grams birthweight children at four years of age and consider the cognitive and behavioural results in the light of gestation, birthweight and socio-economic status.

Children born in 1993 were assessed using the Stanford-Binet Intelligence Scale, Conners' Parent Rating Scales and clinical evaluation. Parent interview provided further information on development, health and behaviour.

Significant differences were demonstrated in a number of comparisons. For the Stanford-Binet results, children >28 weeks gestation obtained higher mean scores than those of shorter gestation for Abstract Visual Reasoning (representing cognitive skills such as spatial perception and visual - motor coordination), and Quantitative Reasoning (which includes numerical ability). In the case of birthweight, the mean score for children > or = 1,000 grams was higher on Quantitative Reasoning than that obtained by the lower birthweight group. When socioeconomic status classification was introduced, a number of differences in test scores were apparent, with children whose parents were in the lowest classification consistently performing less well. Quality of language results followed the same pattern. Analysis of the Conners' Scales identified this low socio-economic status group as having more learning problems and higher scores on the Hyperactivity Index than those whose parents were in the highest socioeconomic status group.

Results for cognitive performance on the Stanford-Binet Scale were within one standard deviation of the mean, for the study population as a group. However, findings suggested that children <1,000 grams birthweight, or <28 weeks gestation, and those <1,500 grams with parents in the lowest socio-economic group, were at particular risk of achieving lower scores prior to school entry. Their pattern of cognitive ability and behaviour could inhibit their adjustment to formal education when complex concepts require problem solving at a more advanced level.