The stability and interrelationships of newborn sucking and heart rate.

The sucking behavior of 44 newborns was recorded along with heart rate (HR) and respiration. These 3 systems showed stability over a 24-hr period. Sucking parameters varied markedly depending upon whether the infant was sucking for sucrose or under a no-fluid condition. Moreover, HR was strikingly affected by sweetness. The direction of HR change was toward increasing rates when sucking for sweet, even though sucking for sweet substances occurs more slowly than for no fluid.