Infant anticipatory stress.

In humans, anticipatory stress involves activation of the limbic-hypothalamic-pituitary-adrenal axis, which releases stress hormones such as cortisol in response to an impending stressor. Conditioning of the stress response to anticipate and prepare for future challenges is a hallmark of adaptation. It is unknown whether human infants in the first year of life have developed the neural circuitry to support the anticipation of stressful events in an attachment context.