Intelligence and reading abilities in eight year old children who failed to thrive in infancy
The aim of the work reported in this thesis was to investigate intelligence and reading ability at school age in a population based sample of children who failed to thrive in the first two years of life. Weights for an annual cohort of term infants, retrieved from clinic records, were compared with weight expected conditional upon early weight. Those with weights in the lowest 5% in two or more age bands (3, 6, 9, 12 and 18 months) were identified as cases (n =136). Cases were stratified by age, sex and deprivation level of their area of residence at eighteen months of age, and the same number of controls selected from each stratum. Two controls were later omitted as they were found to have been born preterm (< 37 weeks). Between ages 7 and 9 years 79% of cases and 82% of controls were traced and studied. Height, head circumference and weight were measured, and an IQ and reading test administered. Information about socio-economic status, family structure and medical history was gathered during a home visit. The mother's height was measured, the father's being reported by the mothers, and the mother's IQ tested. All testing was carried out blind to the child’s case or control status. The child's medical records were retrieved where admission to a hospital or outpatient clinic was reported and the conditions diagnosed were coded blind for their probable effects on cognitive outcomes or growth. At eight years of age mothers in the case group reported more feeding problems in infancy and more organic conditions. Cases were shorter, lighter, thinner and had a smaller head circumference than controls. These anthropometric differences were all statistically significant and remained so after allowing for parental stature. There were no statistically significant differences in IQ and reading ability either before or after adjusting for maternal IQ, organic condition or the few covariates found to differ between the groups.