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Selective improvement in cognitive test scores of extremely low birthweight infants aged between 2 and 5 years
W H Kitchen1, A L Rickards, G W Ford
1Department of Obstetrics and Gynaecology, University of Melbourne, Parkville, Australia.
Insights
Extremely low birthweight (ELBW) children show significant cognitive improvement between ages 2 and 5 years, catching up to larger very low birthweight (VLBW) peers. This suggests developmental delays in ELBW infants may resolve over time.
Area of Science:
- Developmental Pediatrics
- Neuroscience
- Neonatology
Background:
- Extremely low birthweight (ELBW) infants face significant developmental challenges.
- Cognitive development trajectories for ELBW infants require further investigation.
- Understanding catch-up growth in ELBW children is crucial for early intervention.
Purpose of the Study:
- To compare the cognitive development of ELBW children with larger very low birthweight (VLBW) and normal birthweight (NBW) children.
- To determine if cognitive improvements in ELBW infants between 2 and 5 years are real or apparent.
- To identify factors influencing cognitive outcomes in high-risk infant populations.
Main Methods:
- Longitudinal study comparing cognitive scores of ELBW, VLBW, and NBW children at 2 and 5 years.
- Utilized Bayley Scales of Infant Development (MDI) at 2 years and Wechsler Preschool and Primary Scales of Intelligence (WPPSI) at 5 years.
- Standardized cognitive scores relative to NBW children to assess relative change.
Main Results:
- At 2 years, ELBW children had significantly lower Mental Developmental Index (MDI) scores than VLBW and NBW children.
- By 5 years, ELBW and VLBW children showed similar Wechsler Preschool and Primary Scales of Intelligence (WPPSI) scores, though lower than NBW children.
- Standardized scores revealed significant cognitive improvement in ELBW children from 2 to 5 years, unlike VLBW children.
Conclusions:
- ELBW children demonstrate a real catch-up in cognitive development between 2 and 5 years.
- Perinatal and other stresses may require ELBW infants more time to compensate, leading to initial delays.
- Developmental delays observed at 2 years in ELBW infants may not be persistent by age 5.
Abstract:
The cognitive development at 2 and 5 years of a cohort of extremely low birthweight (ELBW) children (birthweight 500-999 g) was compared with that of cohorts of larger very low birthweight (VLBW) children (birthweight 1000-1500 g) and normal birthweight (NBW) children (birthweight greater than 2500 g) to determine whether the improvements in cognitive function of ELBW infants between 2 and 5 years are apparent or real. At 2 years of age, ELBW children had a mean Mental Developmental Index (MDI) on the Bayley Scales of 90.4, significantly lower than the means of 100.3 for the larger VLBW children (P = 0.006), and 107.8 for the NBW children (P = 0.0002). However by 5 years the mean scores on the Wechsler Preschool and Primary Scales of Intelligence (WPPSI) full-scale for the ELBW and larger VLBW children were virtually identical (105.9 and 106.0 respectively)--but still lower than the mean WPPSI full-scale of 114.6 for the NBW children. After standardizing the MDI and WPPSI scores relative to the NBW children, the ELBW children improved between 2 and 5 years (paired t-test, t = 3.2, P = 0.004) whereas the larger VLBW infants did not. We postulate that ELBW children require more time than larger VLBW children after birth to compensate for perinatal and other stresses, and that developmental delay at 2 years may not always persist to 5 years.