Intelligence and executive functions in 9–10 year-old preterm children born with very low and extremely low birth weight

Anett Nagy,Anna Mária Beke,Rózsa Gráf,Endre Horváth,Magda Kalmár

doi:10.1556/0406.20.2019.011

Abstract

Theoretical background: Premature birth is in the focus of research interest as it is the most common perinatal risk endangering the development of children. However, the implications of prematurity for the long-term outcome are far from fully understood. Compromised development of cognitive and executive functions may be underlying academic underachievement in school-age preterm children. Aim: to assess the school-age outcomes of Hungarian VLBW/ELBW preterm children in basic cognitive abilities and executive function as compared to typically developing, full-term children as well as to investigate the background of individual differences. Method: 54 preterm children (27 ELBW, 27 VLBW) and a matched group of 27 healthy full-term children, aged 9–10 years, were tested using the Wechsler Intelligence Scales for Children (WISC-IV), the Corsi Block Tapping Task (digital version) for measuring spatial–visual working memory and the Wisconsin Card Sorting Test (WCST, digital version) for testing cognitive flexibility. As background variables perinatal and socioeconomic factors were entered in the analysis. Results: In each measure of the WISC-IV all three groups performed in the normal range. The ELBW children displayed certain developmental lags. They scored significantly lower in the Full-Scale IQ and the Processing Speed than the other two groups, and in the Perceptual Reasoning and one measure of spatial–visual working memory as compared to the non-risk comparison group. Perinatal complications and maternal education were related to the outcome. Conclusions: With the improved perinatal care preterm children have fair chances for good developmental outcomes. However, the individual variations are great and various perinatal and social factors may hamper the development of cognitive and executive functions. A birthweight below 1000 grams is a notable risk, particularly if combined with perinatal complications.

Highlights

According to an international consensus neonates born before the 37th week of gestation are considered preterms
They were divided into two groups, the first group consisted of the children with very low birth weights (VLBW, 1000–1499 grams) while the children in the second group had extremely low birth weights (ELBW, Birth weight (BW) < 1000 grams)
Some of them suffered certain perinatal complications – mostly of milder degrees (Table 1), and they were free from serious CNS injuries

Summary

Introduction

According to an international consensus neonates born before the 37th week of gestation are considered preterms. According to the degree of immaturity three categories are distinguished: moderate to late preterms (gestational age [GA]: 32–37 weeks), very preterms (GA: 28–32 weeks), extremely preterms (GA < 28 weeks) (WHO, 2018). Birth weight serves as a basis for a classification of preterm neonates most frequently used in medical praxis according to the recommendation by the BNO 10. The Hungarian figures regarding the distribution of the preterm neonates in 2017 were as follows: GA 32–37 weeks 84,6%, GA 28–31 weeks 10,4%, GA 24–27 weeks 4,5%, GA < 24 weeks 0,5%; normal birth weight (> 2500 g) 38%, LBW 46,5%, VLBW 8,7%, ELBW 6,7% (HCSO, 2018). Perinatal characteristics and complications in the preterm children: birth weight, gestational age, bronchopulmonal dysplasia, intraventricular haemorrhage, rethinopathy of prematurity.

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