Prematurity affects cortical maturation in early childhood.

Cortical development in the first years of age for children with very low birth weight is not well characterized. We obtained high-resolution structural magnetic resonance images from children aged 18-22 months (16 very low birth weight/7 term) and 3-4 years (12 very low birth weight/8 term). Cortical surface area and thickness of the brain were assessed using the FreeSurfer data analysis program, and manually inspected for accuracy. For children with very low birth weight, a negative correlation was evident between birth weight and cortical thickness at 18-22 months (P = 0.04), and a positive correlation with cortical surface area at 3-4 years (P = 0.02). Between groups, children with very low birth weight demonstrated a consistent trend for thicker cortices and reduced surface area, compared with control term children (18-22 month surface area, P = 0.08; thickness, P = 0.11; 3-4 year surface area, P = 0.73; thickness, P = 0.14). The normal processes of cortical thinning and surface area expansion in the first several years of age may be delayed by premature delivery, a potentially more prominent effect with greater degrees of prematurity.