Salivary cortisol in infants at daycare and at home

Adrenocortical secretion of cortisol, a product of stress, may have harmful physical and emotional effects. Increased cortisol has been observed in preschoolers at daycare; however the effects of daycare on infant adrenocortical activity remain unknown. A biobehavioral perspective on the developmental integration of behavior and biological processes can serve as a structure for examining cortisol and behavior as well as risk and protective factors for adrenocortical activation, at daycare. With that aim, salivary cortisol was assayed in twenty-five 3-to-18-month-old infants at daycare, thirteen of whom were also sampled at home. Engagement, affect, temperament, and age were examined in relation to cortisol levels at daycare. Results revealed no significant difference between home and daycare cortisol levels. Positive engagement was associated with lower average cortisol levels, distress-prone temperament was associated with less decrease in cortisol over the day, and age appeared to influence cortisol levels, especially in infants 12 months of age and older, who had higher cortisol than younger infants. The temperament scale of Smiling and Laughter was not associated with lower cortisol. It was concluded that positive engagement may buffer cortisol secretion while distress-prone temperament may increase adrenocortical reactivity at daycare. A large scale study including a measure of the quality of infant-teacher and infant-parent relationships would be useful in confirming these results.