Mother-Infant Physiological Coregulation Is Associated With Infant Developmental Status Among Families With Experienced Adversity.

Mother-infant physiological coregulation may vary by the infants' developmental needs. We examined whether infant developmental status was associated with dynamic trajectories of mother-infant respiratory sinus arrhythmia (RSA) coregulation. Fifty-three US mothers and infants oversampled for lower income, higher stress, and child maltreatment risk completed a double Face-to-Face Still-Face (FFSF) paradigm, alternating between play and stress conditions, in which RSA was collected in 30-s epochs. Infant development was measured using the Developmental Assessment for Young Children Socioemotional Skills and Adaptive Behavior subscales and the Survey of Well-Being of Young Children Developmental Milestones subscale. Growth modeling of RSA coregulation across the FFSF indicated two significant interactions: a time × mother RSA × infant socioemotional skills interaction, indicating a dyadic RSA pattern whereby maternal physiological engagement (RSA withdrawal) buffering infant stress (RSA augmentation) was linked to higher infant socioemotional competence; and a condition × infant RSA × developmental milestones interaction, suggesting that in infants with lower developmental milestones, this same dyadic pattern of infant RSA augmentation coupled with maternal RSA withdrawal was more likely during stress conditions. Findings suggest mother-infant RSA coregulation varies by infants' developmental status, with mothers offering more support during challenging contexts. Findings may inform the promotion of adaptive caregiving behaviors and infant development in interventions with high-risk families.