Gestational age at preterm birth in relation to corpus callosum and general cognitive outcome in adolescents.

Prematurity is associated with corpus callosum abnormalities and low general cognitive functioning. The present study explores the specific relationship between gestational age, corpus callosum, and intelligence quotient (IQ) in a sample of preterm-born adolescents. Sixty-four adolescents born at a gestational age of 36 weeks or less were divided into 4 groups attending to their gestational age (GA) (group 1, < or = 27; group 2, 28-30; group 3, 31-33; group 4, 34-36). These individuals were compared with 53 adolescents born at term and of similar age, gender, and sociocultural status. Individuals born at a gestational age of 27 or less (group 1) presented a generalized corpus callosum reduction in the posterior part (posterior midbody, isthmus, and splenium) as well as in the anterior part (anterior midbody and genu), a reduced total white-matter volume, and a low Full-Scale IQ. Group 2 (GA between 28 and 30) also showed a low IQ, but corpus callosum reduction was only found in the splenium, without total white-matter volume reductions. Group 3 (GA between 31 and 33) did not present differences in corpus callosum size or a reduced total white- matter volume, but they showed a low Full-Scale IQ. Group 4 (GA between 34 and 36) did not show a smaller corpus callosum or a lower general cognitive performance. Specific significant correlations were found between corpus callosum subregions and gestational age. These results suggest the importance of gestational age in prematurity in relation to brain structural and functional outcome. Premature babies born at a gestational age of 27 weeks or less are the target group for long-term corpus callosum and white-matter anomalies and for a low IQ.