Maternal psychological stress moderates diurnal cortisol linkage in expectant fathers and mothers during late pregnancy

Using data from a large international sample (N = 385) of first-time expectant parents, the current analysis investigated whether parents demonstrated diurnal cortisol linkage in late pregnancy and whether self-reported psychological stress moderated this linkage. At approximately 36 weeks gestation, mothers and fathers collected saliva samples in their home at three times on two consecutive days and reported on their psychological stress. Results from multilevel models indicated that there was significant positive within-couple diurnal cortisol linkage on average for the whole sample. However, this linkage was moderated by maternal self-reported psychological stress. Specifically, for couples with higher maternal psychological stress, cortisol linkage was strong. Conversely, for couples with lower maternal psychological stress, maternal and paternal cortisol were unrelated. These findings suggest that among higher-maternal-stress couples, lower paternal cortisol may buffer maternal cortisol, whereas higher paternal cortisol may amplify maternal cortisol. Our results support the idea that interpersonal psychological and physiological stress in close relationships is interdependent and mutually influenced. Further, our findings contribute to the field's understanding of interpersonal processes during pregnancy, which may have health-related implications in the prenatal and postnatal periods for both parents and the developing child.