Sequential 22-hour profiles of breathing patterns and heart rate in 110 full-term infants during their first 6 months of life.

Sequential recordings (total number 365, mean duration 22 hours) of ECG and abdominal wall movement were obtained from 110 full-term infants up to 6 months of age. The longest pause in breathing movement per recording (maximum 21.6 seconds) decreased in duration over the first 2 weeks of life (P less than .005). Pauses greater than 18.0 seconds were not detected after seven days. The spread of values for pauses greater than or equal to 3.6 seconds duration was widest during the first 2 weeks, and their number decreased with age (P less than .001). Periodic breathing, detected in 69% to 80% of infants in all age groups, showed decreasing trends with age in total duration and maximum length of episode (P less than .005 for both). The spread of values was widest during the first 2 weeks (range for total duration 0 to 4.7 hours) and decreased with age. The mean respiratory rate during regular breathing decreased after 4 weeks (P less than .001). The spread of values was widest during the first 2 weeks and decreased with age. Birth weight was positively correlated with mean respiratory rate during the first three days of life (r = +.64, P less than .001). The mean heart rate during regular breathing increased during the first 15 days (P less than .001) and then decreased after 4 weeks (P less than .001). Higher mean heart rates were found in male infants (P less than .01).