Impact of maternal trauma-related psychopathology and life stress on HPA axis stress response

To understand and curb intergenerational transmission of stress-related disorder, it is important to identify how trauma-related psychopathology in mothers impacts their psychophysiological stress regulation, particularly in the context of parenting their infants. In this study we investigated associations between mothers' trauma-related psychopathology and life stress and HPA axis response to a personally relevant stressor (infant separation stress) in a non-clinical sample followed longitudinally postpartum. A community sample of low-income mothers (n = 73) and their infants completed laboratory sessions at 3, 6, 12, and 18 months postnatal, and salivary cortisol samples collected before and after dyadic stress tasks at the latter three sessions. These tasks were used to assess HPA function. A three-level hierarchical linear model of repeated cortisol measures nested within sessions within mother-infant dyads did not reveal significant main effects of trauma-related psychopathology on maternal cortisol response, but there was evidence that both a clinical interviewer-rated diagnosis of PTSD and ongoing self-reported trauma symptoms blunted effects of life events on cortisol reactivity. Region of significance analyses indicated that current life stress predicted more pronounced cortisol reactivity only among mothers without trauma-related psychopathology; for those with trauma-related psychopathology, life stress did not relate to cortisol response. Effects held when controlling for childhood trauma and previous (prenatal) maternal distress symptoms, suggesting they did not reflect ongoing impacts of past trauma exposure and/or psychopathology. Blunting effects of trauma-related psychopathology on maternal life stress responsiveness may help clarify how stress sensitivities and mental health are transmitted from parent to child.