Predicting cardiac vagal regulation in early childhood from maternal-child relationship quality during toddlerhood.

The aim of this study was to examine the influence of maternal-child relationship quality during toddlerhood on early childhood physiological regulation. A community sample of 447 children (215 males) was recruited at age 2 for participation in the study using the Child Behavior Checklist [Achenbach [1992] Manual for the child behavior checklist/2-3 & 1992 profile. Burlington, VT: University of VT Department of Psychiatry]. Mothers and children were observed across several interactions in the laboratory at age 2 and mothers completed the Parenting Stress Index [Abidin [1995] Manual for the parenting stress index. Odessa, FL: Psychological Assessment Resources]. Relationship quality was assessed using laboratory measures of hostility, positive guidance, and stress related to the quality of the relationship as reported by mothers. Cardiac vagal regulation at age 2 was assessed across six challenge tasks, three in which the child and mother worked together and three in which the child worked independently, and was indexed by the magnitude of vagal withdrawal (decrease in respiratory sinus arrhythmia, RSA) to challenge. Results indicated that children displayed greater cardiac vagal regulation and heart rate acceleration during collaborative tasks versus independent tasks. In addition, maternal-child relationship quality predicted the degree of vagal regulation in children at age 5, even after controlling for early and concurrent level of behavior problems as well as 2-year cardiac vagal regulation. Children with poorer quality relationships displayed significantly poorer vagal regulation and lower heart rate acceleration (p < .01). These findings are discussed in terms of the implications of environmental factors for the acquisition of fundamental self-regulatory skills.