Oehler’s49 study is the only one within this review
that stratified infants on the basis of their severity of
illness scores and head circumference. Stratifying on
the basis of the infant’s degree of illness is important
because very preterm infants with major medical
factors and a high severity of illness will likely be
limited in their ability to regulate incoming sensory
stimulation. Likewise, infants with restricted head
growth are more likely to have poorer neurodevelopmental
outcomes