Investigators at University of California, San Diego, and centers in Hawaii and Trondheim, Norway, examined structural growth trajectories and rates of change in the whole brain and regions of interest in infants during the first 3 months after birth. Serial structural T1-weighted and/or T2-weighted MR images were obtained from 87 healthy term-born infants, aged 2 to 90 days. Whole-brain volume at birth was one-third of healthy elderly brain volume, with no gender differences. Growth rate was 1%/day, slowing to 0.4%/d by the end of the first 3 months. Overall growth in the first 90 days was 64%; male brain growth was faster than female. Longer gestation was associated with larger brain size. Expected brain size of an infant born one week earlier than average was 5% smaller than average. The cerebellum grew at the fastest rate, more than doubling in 90 days; and the hippocampus grew at the slowest rate, increasing by 47% in 90 days. The left lateral ventricle was larger than the right, and left-right asymmetry occurred in multiple regions of interest. MR imaging can be used to detect deviant maturational patterns indicative of neurodevelopmental disorders. 
COMMENTARY. An MRI study to show a relationship between head circumference and brain growth in preterm infants found that brain volume is a determinant of head size at term. Microcephaly is associated with a reduction of brain tissue volumes, especially deep nuclear gray matter, showing a selective vulnerability of basal ganglia. Poor postnatal head growth in preterm infants becomes more evident by 2 years and is strongly associated with poor neurodevelopmental outcome and cerebral palsy .
An MRI study of the relationship between growth status and regional brain volume in premature babies at term-equivalent age showed a positive correlation between fractional anisotropy (FA) and head circumference and body weight. Body weight was the only significant predictor for FA (P<0.05) and white matter microstructure in brain areas related to attention, language, cognition, memory, and executive functioning .