Imaging Reveals Effects of Preterm Birth

In a new study, magnetic resonance imaging (MRI) scans and cognitive testing of eight-year old children revealed that preterm birth is associated with long-term reductions in brain volume and correlates significantly with IQ (intelligence quotient) measures. These findings suggest that disturbances in cerebral development account for cognitive deficits in preterm infants. The study was published in the The Journal of the American Medical Association (JAMA, 2000;284:1939-1947).

The study involved 25 preterm children who weighed 600-1250 g at birth and 39 control children. The researchers used MRI scans to measure regional brain volumes of the subjects. Next, they examined the association of regional volume with the results of cognitive tests. This showed that full-scale, verbal and performance IQ scores were positively associated with regional brain volume, most strongly with volumes of sensorimotor and midtemporal brain regions. The researchers found similar correlations between brain volume and some perinatal variables, such as gestational age and Apgar score, but not between brain volume and such variables as birth weight, maternal age, and the presence of bronchopulmonary dysplasia.

The researchers are unable to say precisely what caused the brain abnormalities. They conclude that a premature transition from intrauterine to extrauterine life can profoundly disrupt the development of fetal brains. Longitudinal imaging studies of preterm infants, they note, will help to elucidate the role of physiologic stresses. The study was conducted by researchers at Yale University School of Medicine (New Haven, CT, USA) and Brown University School of Medicine (Providence, RI, USA).