Examining the implications of contextual stress and maternal sensitivity for infants' cortisol responses to the still face paradigm

Infants' hypothalamic-pituitary-adrenocortical (HPA) axis responses to acute stressors are theorized to be shaped by parents' sensitive responsiveness to infants' cues. The strength and direction of the association between maternal sensitivity and infants' HPA responses may depend on the context in which maternal sensitivity is observed and on broader environmental sources of stress and support. In this preregistered study, we used data from 105 mothers and their 7-month-old infants to examine whether two empirically identified forms of contextual stress-poor maternal psychosocial wellbeing and family socioeconomic hardship-moderate the association between maternal sensitivity and infants' cortisol responses to the Still-Face Paradigm (SFP). Results indicated that maternal sensitivity during the free play and family socioeconomic hardship interacted to predict infants' cortisol responses to the SFP. Specifically, maternal sensitivity during this non-distressing interaction was negatively associated with cortisol responses only among infants whose mothers were experiencing relatively high socioeconomic hardship. Exploratory analyses revealed that poor maternal psychosocial wellbeing was positively associated with overall infant cortisol production during the SFP. Altogether, these findings suggest that experiences within early parent-infant attachment relationships and sources of contextual stress work together to shape infant HPA axis activity.