Heart Rate and Respiratory Rate Differences Between Preterm and Full-Term Infants During Quiet Sleep: Possible Implications for Sudden Infant Death Syndrome

Abstract

The heart rate and respiratory rate of 8 preterm (average gestational age, 33.3 .+-. 2.2 wk) and 13 full-term infants were determined during quiet sleep at home during the 1st yr of life. Both heart rate and respiratory rate were greater in preterm infants throughout the 1st 6 mo. The difference was maximum at age 10 wk (21.1 beats/min and 13.7 breaths/min), with the difference being statistically significant, at least at the P < .01 level at ages 10, 12 and 14 wk, while P .gtoreq. .01 at all other ages. The 10 to 14 wk period is precisely the same period during which the incidence of sudden infant death syndrome (SIDS) is maximum. The concept that SIDS is linked to a vulnerable phase of cardiorespiratory maturation was supported.