Newborn Brain: Body weight ratios.

Newborn brain:body weight ratios are generally considered to be constant in man. In autopsy studies many factors influence the measured weight of the brain, and therefore the conclusions based on such observations, including the gestational age of the material, the presence or absence of intrauterine growth retardation, and the cause of death. In this study these influences have been eliminated by careful selection of normally grown fullterm newborns not subject to the factors influencing brain weight. Using double logarithmic plots, brain size in fullterm newborns is found to be related to the 0.64 power of birth weight. There is a negative correlation between relative brain size and increasing fullterm birth size in man.