Does a bigger brain make for a smarter child in babies born prematurely?

"In babies born preterm, the more the cerebral cortex grows early in life the better children perform complex tasks when they reach six years old," said study author A. David Edwards, DSc, of Imperial College in London. "The period before a full-term birth is critical for brain development. Problems occurring at this time have long-term consequences, and it appears that preterm birth affects brain growth."

The study looked at brain growth rates of 82 infants who were born before 30 weeks gestational age using MRI scans of their brain between 24-44 weeks. Brain scans were collected repeatedly from immediately after the babies were born until their full-term due date. Their cognitive abilities were tested at two years old and again at six years old.

The study found that the faster the rate of cerebral cortex growth in infancy, the higher their scores were on the developmental and intelligence tests as children. A five to 10 percent reduction in the surface area of the cerebral cortex at full-term age predicted approximately one standard deviation lower score on the intelligence tests in later childhood. Motor skills were not correlated with the rate of cerebral cortex growth, and the overall brain size was not related to general cognitive ability.

"These findings show we should focus on the growth of specific regions of the brain like the cortex when trying to understand or diagnose potential problems in babies and fetuses," said Edwards.

The study was supported by the Health Foundation, the Garfield Weston Foundation, Wellbeing of Women and the NIHR Imperial College Healthcare Comprehensive Biomedical Research Center.