Neonatal cardiac vagal tone and school-age developmental outcome in very low birth weight infants.

Twenty very low birth weight (VLBW) children participated in a longitudinal follow-up study designed to explore the relation between neonatal physiological measures and school-age (6-9 years) outcome measures. Neonatal measures of mean heart period and cardiac vagal tone (respiratory sinus arrhythmia, RSA) were derived from weekly recordings at 33, 34, and 35 weeks gestational age. An RSA Maturation measure was calculated across the 3-week period to assess functional changes in vagal regulation of the heart during a period in which there is enhanced myelination of the vagus. In addition, the relation of neonatal risk measures (low birth weight, low socioeconomic status, high medical risk) and preschool measures (behavior, cognitive abilities) to school-age outcome measures was examined. As expected, school-age measures were closely related to preschool measures within the same domain. Neonatal risk measures were not related to school-age outcome measures. Of the neonatal physiological measures, RSA maturation was correlated with a single school-age measure, social competence as measured by the Child Behavior Checklist (Achenbach, 1988). Partial correlation and multiple regression analyses were used to further explore the relationship between neonatal RSA maturation and school-age social competence. Results support the hypothesis that early central nervous system self-regulatory abilities, as assessed by RSA measures, are predictive of later complex behaviors.