Growth hormone limits the brain/body development before birth in relation to sex, grasp-reflex asymmetry and familial sinistrality of human neonates.

Since there is no theological explanation for high growth hormone (GH) concentrations in perinatal blood, GH concentrations from umbilical cord blood were studied in relation to body weight and head circumference (brain weight) in the human neonates. GH exhibited inverse correlations with body weight and head circumference in these subjects, which depended upon sex, familial sinistrality (FS), and grasp-reflex dominance. This implies that GH may adversely influence the brain/body development during perinatal development on the basis of a genetically predetermined brain organization. It was suggested that the lipolytic and anti-insulin GH effects may be responsible for its body-weight reducing effects; the anti-insulin GH actions may be responsible for its brain-weight reducing effects. As a result of these actions, GH may limit the brain/body development, to induce a balanced growth during perinatal period.