Behavioral Genetics:  Research Article

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Neurologic and Developmental Disability after Extremely Preterm Birth

CITATION:  Marlow, N., Wolke, D.M., et al.  Neurologic and Developmental Disability at Six Years of Age after Extremely Preterm Birth.  New England J of Medicine, vol. 352, No.1. pp 9


Background.  Birth before 26 weeks of gestation is associated with a high prevalence of neurologic and developmental disabilities in the infant during the first two years of life.

Methods.  We studied at the time of early school age children who had been born at 25 or fewer
completed weeks of gestation in the United Kingdom and Ireland in 1995. Each child had been evaluated at 30 months of age. The children underwent standardized cognitive and neurologic assessments at six years of age. Disability was defined as severe (indicating dependence on caregivers), moderate, or mild according to predetermined criteria.

Results.  Of 308 surviving children, 241 (78 percent) were assessed at a median age of six years
and four months; 160 classmates delivered at full term served as a comparison group. Although the use of test reference norms showed that cognitive impairment (defined as results more than 2 SD below the mean) was present in 21 percent of the children born extremely preterm (as compared with 1 percent in the standardized data), this value rose to 41 percent when the results were compared with those for their classmates. The rates of severe, moderate, and mild disability were 22 percent, 24 percent, and 34 percent, respectively; disabling cerebral palsy was present in 30 children (12 percent). Among children with severe disability at 30 months of age, 86 percent still had moderate-to-severe disability at 6 years of age. In contrast, other disabilities at the age of 30 months were poorly predictive of developmental problems at 6 years of age.

Conclusions.  Among extremely preterm children, cognitive and neurologic impairment is common
at school age. A comparison with their classroom peers indicates a level of impairment that is greater than is recognized with the use of standardized norms.


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