| Abstract | In 21 healthy full-term neonates, 122 10-min recordings of ECG and CO2 respirograms were made during the first 5 days of life. Records were analyzed with a digital computer, using stochastic point process analysis techniques to characterize variations in heart and respiration rates. Mean heart rate was 114/min, and mean respiration rate 46/min. For heart rate, the root mean square (RMS) difference from mean (overall variation) was 40 msec, and interval-to-interval variation (RMS of successive differences) was 25 msec; the corresponding values for respiration rate were 598 msec and 770 msec, respectively. Periodic heart rate variation (periodicities in the range 1-2 sec or 10-29 sec) was found in 8 records from 7 infants. Random heart rate variation was usually Markoffian type, inter-interval dependence extending over at least 5 successive intervals. No significant periodic variation or interdependence of intervals was detected in respiration rate, which thus appears to have certain Gaussian random properties. Apneic periods of at least 5 seconds occurred 6.6/hour. The findings indicate a strong short-range control of cardiac rate but not of respiration. |