Mother-infant physiological synchrony in the context of childbirth-related posttraumatic stress symptoms

Synchrony in mother-infant interactions is crucial for infant development. However, mother-infant physiological synchrony in the context of maternal childbirth-related posttraumatic stress symptoms (CB-PTSS) remains unknown. This pilot study aimed to investigate physiological synchrony within the context of CB-PTSS. Additionally, it investigated the association between mother-infant physiological synchrony and reciprocity. A total of 86 French or English-speaking mothers and their term infants participated in the study. Maternal CB-PTSS was assessed using the PTSD Checklist for DSM-5 (PCL-5), modified for childbirth. Mother-infant dyads were classified into three groups based on their responses to the PCL-5. During mother-infant interactions, physiological synchrony was measured using heart rate variability (HRV), while reciprocity was observed in video recordings. Cross-lagged analysis revealed distinct patterns of HRV fluctuations between mother-infant dyads: positive (mother and infant HRV fluctuated in the same direction) or negative (mother and infant HRV fluctuated in the opposite direction). To avoid canceling out potential effects by averaging the positive and negative correlation coefficients, we analyzed them separately. In positive dyads, maternal HRV led infant HRV by approximately two seconds. Conversely, in negative dyads, there was no significant lag or lead observed in either direction. Our analysis did not reveal a significant impact of CB-PTSS group classification on the physiological synchrony between mothers and their infants. Additionally, we found no significant relation between physiological synchrony and reciprocity within the dyads. We recommend that future studies with a similar focus should control for factors such as individual physiological regulation, maternal anxiety, and maternal depression to further explain these relationships.