Maternal cortisol and parenting in infants’ first 6 months: The moderating role of family stress.

The present study examined the joint effect of maternal hypothalamic–pituitary–adrenal (HPA) axis activity and family contextual stress on maternal bedtime parenting (i.e., emotional availability; EA) during the first 6 months postpartum. On each occasion, maternal HPA axis activity was indexed using total diurnal cortisol output (i.e., area under the curve with respect to ground) and diurnal cortisol change from afternoon to bedtime. The composite score of family contextual stress was calculated by averaging the standardized score of paternal and maternal educational level (reversed), family income-to-needs ratio (reversed), household chaos, and maternal negative life events. The multilevel models showed that greater contextual stress was associated with lower bedtime parenting quality in mothers. In addition, maternal diurnal cortisol interacted with contextual stress to predict parenting over time. At the between-person level, only among mothers with higher contextual stress, mothers with flatter cortisol declines, showed greater decreases in parenting quality from 1 to 6 months, compared to those with steeper cortisol declines. At the within-person level, for a given mother who experienced high contextual stress, parenting quality decreased on the occasion when her total cortisol output increased. The effects of cortisol indicators on parenting were not significant among mothers from families with low contextual stress.