AbstractRelease of adrenal medullary hormones as a result of activating the orthostatic pressor reflex may influence human infants' later behavior. The amount of time mothers held their infants in an upright position during the 1st and 3rd months postpartum was negatively related to the same children's tendency to cope with difficulties encountered in manipulating inanimate objects at the age of 30 months. This effect may represent a physiological response to early maternal handling.