BACKGROUND: Mothers have been shown to have higher morning cortisol on days they go to work compared to non-workdays; however, it is unknown how maternal workday associates with child morning cortisol or the attunement of mother-child morning cortisol. AIMS: This study examined the presence and stability of morning cortisol levels and slopes (i.e., cortisol awakening response or CAR) in a sample of 2-4year old children in out-of-home child care with working mothers. In addition, we examined the differential contributions of maternal workday on mother-child attunement in morning cortisol. METHOD: Mother and child morning cortisol was sampled twice a day (awakening and 30min later) across four consecutive days (2 non-workdays; 2 workdays) among 47 working mothers and their young children. Mothers also reported on compliance with sampling procedures and provided demographic information. RESULTS: While children exhibited stability in cortisol levels, children's CARs were variable, with children's non-work CARs not predictive of work CARs. Similarly, a significant morning rise in cortisol was only found on workdays, not non-workdays. Overall, mothers had higher cortisol levels and steeper CARs than their children. Further, maternal workday moderated the attunement of mother-child morning cortisol, such that mothers and children had concordant cortisol levels on non-workdays, but discordant cortisol levels on workdays. CONCLUSIONS: Morning cortisol may be more variable in pre-school aged children than adults but may be similarly responsive to the social environment. Further, workday mornings may be a time of reduced mother-child cortisol attunement.
