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Effect of very low birth weight and subnormal head size on cognitive abilities at school age
M Hack1, N Breslau, B Weissman
1Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH.
Insights
Very-low-birth-weight infants with subnormal head size at eight months show poorer cognitive and academic outcomes. These findings highlight the importance of head circumference monitoring for predicting long-term neurodevelopmental trajectories.
Area of Science:
- Pediatrics
- Neurodevelopmental Pediatrics
- Growth and Development
Background:
- Very-low-birth-weight (VLBW) infants often experience perinatal growth failure.
- Head size at eight months corrected for prematurity can indicate persistent growth issues.
Purpose of the Study:
- To test if VLBW infants with subnormal head size at eight months have poorer growth and neurocognitive abilities at school age.
- To determine if these differences persist after controlling for major neurologic impairment and other risk factors.
Main Methods:
- A cohort of 249 VLBW children born between 1977-1979 was followed.
- At eight to nine years of age, children underwent neurologic examinations and extensive neurocognitive testing.
Main Results:
- 13% of VLBW infants had subnormal head size at eight months.
- Subnormal head size at eight months correlated with lower birth weight, higher neonatal risk scores, and increased neurologic impairment at school age.
- Even without neurologic abnormalities, subnormal head size predicted poorer IQ, language, academic aptitude, and increased hyperactivity.
Conclusions:
- Perinatal growth failure, indicated by subnormal head circumference at eight months in VLBW infants, is linked to adverse cognitive, academic, and behavioral outcomes at eight years.
- Head size at eight months serves as a significant indicator of neurodevelopmental prognosis in VLBW children.
Background:
We tested the hypothesis that very-low-birth-weight (less than 1.5 kg) infants with perinatal growth failure whose head size is not normal by eight months of age (corrected for prematurity) have significantly poorer growth and neurocognitive abilities at school age than very-low-birth-weight children with a normal head size at eight months. We also hypothesized that these differences would persist even after control for major neurologic impairment and perinatal and sociodemographic risk factors.
Methods:
We have followed a cohort of very-low-birth-weight children since their birth during the period 1977 to 1979. At eight to nine years of age 249 children were evaluated with a neurologic examination and tests of intelligence; receptive and expressive language skills; speech, reading, mathematics, and spelling aptitude; visual and fine motor abilities; and behavior. Ages were corrected for premature birth.
Results:
Among these 249 very-low-birth-weight children, head size was subnormal (less than the mean -2 SD for age) at birth in 30 (12 percent), at term in 57 (23 percent), and at eight months in 33 (13 percent). As compared with the 216 children with normal head sizes, the 33 children with subnormal head sizes at the age of eight months had significantly lower mean birth weights (1.1 vs. 1.2 kg) and higher neonatal risk scores (71 vs. 53) and at the age of eight years had a higher incidence of neurologic impairment (21 percent vs. 8 percent) and lower IQ scores (mean verbal, 84 vs. 98). Even among the children without neurologic abnormalities, a subnormal head size at eight months of age was predictive of poorer verbal and performance IQ scores at eight years of age; lower scores for receptive language, speech, reading, mathematics, and spelling; and a higher incidence of hyperactivity. In multiple regression analyses to control for socioeconomic and neonatal risk factors, intrauterine growth failure, birth weight, and neurologic impairment, a subnormal head size at eight months of age had an independently adverse effect on IQ and on scores for receptive language, speech, reading, and spelling.
Conclusions:
In very-low-birth-weight infants, perinatal growth failure, as evidenced by a subnormal head circumference at eight months of age, is associated with poor cognitive function, academic achievement, and behavior at eight years of age.