Postnatal Head Shrinkage in Small Infants

Abstract

The fronto-occipital circumference, fronto-occipital and biparietal diameters, degree of suture overriding and weight were measured daily during the 1st wk of life in 50 infants of birth weight under 2000 g. In a 2nd similar group of 21 infants, fronto-occipital circumference, weight and Na balance were measured daily during the 1st wk of life. Head volumes were estimated from the circumference and diameters of the head. The parameters of head size and derived volumes changed maximally and significantly in the direction of intracranial shrinkage around 3 days of age. The degree of shrinkage was significantly correlated (P < .005) with the degree of weight and cumulative Na losses, and decreasing gestational age. Postnatal head shrinkage may result from a shift of Na and water outward from the intracranial cavity as a transient phenomenon during the 1st wk of life. The significance of head shrinkage is discussed.