The growth of
head circumference, an indicator of brain development, is not lower during premature hospitalization in infants fed human milk, even when the breastfed infant weighs
less.
[Fully human milk - fed preemies experienced slightly slower growth and
lesser early bone mineral content but no reduction in
head circumference; an indicator of brain development.]
The study also showed that the genetic influences on intelligence are highly correlated with genetic influences on educational attainment, and also, albeit
less strongly, with smoking cessation, intracranial volume,
head circumference in infancy, autism spectrum disorder and height.