AUTONOMIC FUNCTION IN THE NEONATE: VII. MATURATIONAL CHANGES IN CARDIAC CONTROL

Abstract

Cardiac-rate changes with abdominal air-stream stimulation were studied in 14 normal infants during the newborn period and the subsequent 5 months of life. By 2% months the response pattern had changed significantly. This was characterized by a faster reaction, attenuated initial rise in rate, and generally a greater return to below prestimulus levels. In the older infants the overall heart rates were higher than in their respective newborn periods and during crying often achieved levels of 220-230 beats/minute. Response measures at 2% and 5 months of age were often significantly correlated, demonstrating increasing stability after the newborn period. In the light of animal studies indicating early maturational changes in autonomic nervoussystem function, it is hypothesized that significant changes in cardiac control mechanisms occur in the first months of life in the human infant.