Chronic stress and hair cortisol concentration in mothers: A two-study investigation.

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is one mechanism through which chronic stress during pregnancy and parenthood may affect parental, child, and family health. Hair cortisol concentration (HCC) may be well-suited to elucidate associations between chronic stress and HPA axis regulation because HCC reflects cortisol output over several months. However, most previous studies that examine chronic stress in conjunction with cortisol in pregnant individuals or mothers use measures that reflect HPA axis output over a relatively limited time. We report findings from two longitudinal studies that tested associations between chronic stress and HCC in women during the perinatal period (Study 1; n = 144) and mothers of young children (Study 2; n = 102). Both studies measured chronic stress with a measure developed to comprehensively assess chronic stressors in community samples. Hair samples were collected three times in Study 1 (mid-pregnancy, one month postpartum, and 12 months postpartum) and twice in Study 2, approximately one year apart. Chronic stress was associated with higher HCC in both studies. Exploratory analyses indicated that the strength of associations between chronic stress and HCC differed as a function of the life domain of chronic stress. Chronic work and family demands were associated with higher postpartum HCC in Study 1 whereas neighbourhood/housing and discrimination chronic stress were associated with higher HCC in Study 2. These findings provide evidence of a biological pathway through which chronic stress may influence health in mothers and support the utility of hair cortisol as a neuroendocrine measure of chronic stress during pregnancy and parenthood.