The effect of nonnutritive sucking on heart rate in preterm infants.

A laboratory and a field experiment used within-subject designs to test the hypothesis that nonnutritive sucking (NNS) reduces heart rate (HR) in preterm infants. Infants in Experiment A were provided a standard pacifier nipple for 30 min under strictly controlled conditions. In the field Experiment B, nursing staff provided infants with a standard pacifier during alternate intervals in a sequence of four interfeed intervals spanning 12 hr. NNS significantly reduced average HR in each experiment. Given the strongly positive relationship between HR and energy expenditure, these results suggest that NNS reduces energy expenditure in preterm infants. Such an effect, in turn, could help to explain how the opportunity to engage in NNS enhances growth in preterms.