Stress responses of infants and mothers to a still-face paradigm after traumatic childbirth

Introduction: One-third of women experience childbirth as traumatic and some develop symptoms of childbirthrelated posttraumatic stress symptoms (CB-PTSD symptoms). Whether CB-PTSD symptoms negatively impact on physiological and psychological stress responses in mothers and their offspring and whether they are associated with mother-infant synchrony is not clear. This study aimed to investigate stress responses of (1) mothers with CB-PTSS, (2) of their infant, and (3) the physiological mother-child-synchrony at six months postpartum. Method: Psychophysiological (cortisol and vagal tone) and psychological stress responses of mothers and infant's (n=31 dyads) from the Swiss TrAumatic biRth Trial (NCT03576586) were assessed during a face-to-face still-face paradigm (FFSF-R). Results: There was a significant time effect in maternal stress responses for salivary cortisol, vagal tone, and for maternal subjective stress. As expected, mothers' subjective stress increased during the stress task and mothers vagal tone changed during the first stressful period but not during the second, whereas cortisol unexpectedly decreased over the FFSF-R. Infant negative mood increased over the experiment, but there were no physiological changes. However, a significant interaction effect for mother-infant synchrony during the second reunion period of the FFSF-R was found. Conclusion: Although mothers and their infants were subjectively stressed, they showed only limited physiological stress responses.