VAGAL REGULATION OF HEART-RATE IN THE PREDICTION OF DEVELOPMENTAL OUTCOME FOR VERY-LOW-BIRTH-WEIGHT PRETERM INFANTS

To investigate heart rate and respiratory sinus arrhythmia (RSA) as ma rkers of developmental outcome, infant ECG and 3 year outcome were ass essed in 41 very low birth weight (<1,500 g) infants. Measures of mean heart rate and RSA, and the maturational shifts in their values from 33 to 35 weeks gestational age, were recorded. RSA measures predicted 3 year outcome beyond the effects of birth weight, medical risk, and s ocioeconomic status. Higher RSA was associated with better social skil ls, whereas greater RSA maturation was associated with better mental p rocessing and gross motor skills. Lower heart rate was associated with better behavior regulation and social skills, whereas greater maturat ional decreases were associated with better gross motor skills. Dividi ng the sample into groups of infants with birth weights less than 1,00 0 g and those with birth weights over 1,000 g, RSA maturation emerged a strong predictor of mental processing, knowledge base, and gross mot or skills in the former. A measure of joint maturation of RSA and hear t rate was associated with better behavior regulation at 3 years, as m easured by Child Behavior Checklist and Parenting Stress Index scores, for this group. The findings directly respond to the need for physiol ogical variables in the prediction of outcome in high-risk infants.