The differential leukocyte count was studied within the first 24 hours of life in 115 infants of diabetic mothers (IDMs) appropriate for gestational age (AGA), 16 IDMs large for gestational age (LGA), 104 infants of non-diabetic mothers (INM's) AGA, and 22 INMs-LGA. A significant "shift to the left" was found in IDM's-LGA only. The usual cause of "shift to the left" such as maternal hypertension or fever, respiratory distress syndrome, meconium aspiration, neonatal asphyxia, sepsis, convulsions, or hypoglycemia could not explain this finding. It is hypothesized that increased glucocorticoid secretion may possibly play a role.