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Large variability in performance IQ associated with postnatal morbidity, and reduced verbal IQ among school-aged
1Department of Pediatrics, International Pediatric Growth Research Center, Institute of the Health of Women and Children, The Queen Silvia Children's Hospital, Göteborg, Sweden. jane.gabrielson@vgregion.se
Insights
Preterm school-aged children often show reduced verbal skills, regardless of health complications. Performance abilities vary significantly and are linked to their postnatal health and birth weight.
Area of Science:
- Pediatric Neurology
- Developmental Psychology
- Neonatology
Background:
- Premature birth (<29 weeks gestation) presents risks for neurodevelopmental outcomes.
- Cognitive abilities in school-aged children born preterm require ongoing assessment.
- Postnatal morbidity can impact long-term health and development in this population.
Purpose of the Study:
- To evaluate cognitive functions in a population-based cohort of school-aged children born preterm.
- To investigate the relationship between cognitive performance and postnatal morbidity in this group.
Main Methods:
- A cohort of 51 preterm children (born 1988-1991, <29 weeks gestation) were assessed at a median age of 10 years.
- Cognitive abilities were evaluated using the Wechsler Intelligence Scale for Children (WISC-III).
- Test results were compared against an age-matched normative group, and correlated with postnatal health data.
Main Results:
- 30% of preterm children scored below average (IQ < 80) on Full Scale IQ (FSIQ).
- A significant majority (84%) exhibited below-average Verbal IQ (VIQ), while Performance IQ (PIQ) showed high variability.
- Lower PIQ was associated with high postnatal morbidity and low birthweight, whereas higher PIQ correlated with low morbidity and higher birthweight.
Conclusions:
- Preterm children demonstrate reduced verbal capacity, independent of postnatal health status.
- Performance capacity shows significant variability linked to postnatal morbidity and birth weight.
- Distinct mechanisms appear to influence verbal versus performance outcomes in preterm children.
Aim:
To assess cognitive ability in a population-based group of prematurely born school-aged children and to relate these findings to postnatal morbidity.
Method:
The study group consisted of a cohort of 51 children born preterm, 43 (26 boys, 17 girls) of whom were available for psychological evaluation At evaluation, their median age was 10 y (range 8-11 y). They were all born between 1988 and 1991, with gestational age less than 29 wk (median 27, range 24-28). Their median birthweight was 1060g (range 450-1450). The Wechsler Intelligence Scale for Children (WISC-III) was used, and the test results were compared with those of a standardized, age-matched, normative group of children.
Results:
Thirteen children (30%) performed below average [intelligence quotient (IQ) < 80] for Full Scale IQ (FSIQ). Thirty-six children had a Verbal IQ (VIQ) below the mean value of 100 [84%, 95% confidence interval 73-95%], p < 0.0001. The Performance IQ (PIQ) was within the expected range of a normal population, although a large variability was observed. Discrepancies between VIQ and PIQ of more than 15 IQ units were found in 42% of the children. High postnatal morbidity (days with assisted ventilation, number of blood transfusions) and low birthweight standard deviation scores (SDS) were associated with lower PIQ than VIQ, while low postnatal morbidity and high birthweight were associated with higher PIQ than VIQ.
Conclusion:
This cohort of preterm children had reduced overall verbal capacity independent of morbidity, and a large variability in performance capacity that was associated with postnatal morbidity. The findings suggest that there are different mechanisms influencing the outcome of verbal and performance capacity in preterm children.