Sex differences in cerebral volumes of 8-year-olds born preterm.

We investigate sex-associated effects of preterm birth on cerebral gray matter (GM) and white matter (WM) volumes. Preterm children (n=65) and 31 healthy, term control children had usable magnetic resonance imaging (MRI) data acquired at 8 years of age. Both GM and WM volumes were significantly reduced in the preterm group compared with controls. However, only males with preterm birth had significantly reduced WM compared with term males (P=.021), whereas WM volumes were equivalent in the female groups. Lower birth weight was associated with reduced WM in both boys and girls with preterm birth, whereas intraventricular hemorrhage (IVH) was associated with reduced GM in girls only. Positive correlations between GM and cognitive outcome were observed in girls with preterm birth but not boys. We conclude that preterm birth has a significant impact on brain development with increased risk for smaller GM and WM cerebral volumes. Males appear particularly vulnerable to adverse effects of preterm birth on WM development. However, girls with preterm birth show stronger correlations between neuro-anatomical variables and both neonatal risk factors and cognitive outcome, compared with boys. These findings indicate that the sex of the very preterm newborn influences the mechanisms by which the developing brain is affected.