Oxytocin dynamics and synchrony in mother-child dyads: Long-term neuroendocrine effects of maternal institutionalization

Early institutional care (IC; orphanage) is a severe form of early psychosocial deprivation with documented long-term effects on social and caregiving functioning. Despite longstanding interest in oxytocin (OT) as a key neuroendocrine modulator of affiliative behavior and stress, OT dynamics and synchrony during mother-child interaction among mothers with IC history remain poorly understood. To our knowledge, this is the first study to characterize maternal and child OT responses and dyadic OT covariation in this population. We measured salivary OT in mothers with IC history and mothers raised in biological family care (BFC), and in their children, at baseline and after a structured mother-child interaction. OT response was defined as post-interaction OT after accounting for baseline OT. The sample included 53 mothers (36 BFC; 17 IC) and 44 children (32 BFC; 12 IC). Baseline and post-interaction OT levels did not differ between maternal groups in either dyadic member. However, statistically significant pre-post decline was revealed in BFC mothers but not IC mothers. Maternal OT response differed by maternal IC history: baseline OT predicted OT response among IC mothers but not among BFC mothers, and between-group differences in OT response were detectable primarily at average-to-higher (z ≥ -0.19) baseline OT, with a flatter pattern of baseline-to-post decrease in IC mothers than in BFC mothers at higher baseline OT. After accounting for baseline OT, children of IC mothers had lower post-interaction OT than children of BFC mothers; maternal age and depressive symptoms also contributed to child OT response variability. Dyad-level analyses indexed OT synchrony as correlation-based covariation between maternal and child OT measures and provided suggestive evidence of synchrony in BFC dyads at baseline and for OT response, whereas comparable correlations were not detected in IC dyads; between-group contrasts in these correlation-based indices were not consistently significant. Together, these findings extend IC research into an intergenerational parenting context and identify baseline-dependent maternal OT response and child OT response as candidate targets for replication in larger, multimodal studies integrating behavioral measures and stress physiology.