Associations between respiratory arrhythmia and fundamental frequency of spontaneous crying in preterm and term infants at term-equivalent age.

Abstract

ABSTRACTThis study investigated whether lower vagal function in preterm infants is associated with increased fundamental frequency (F 0; frequency of vocal fold vibration) of their spontaneous cries. We assessed respiratory sinus arrhythmia (RSA) during quiet sleep as a measure of vagal function, and its relationship with the F 0 of spontaneous cries in healthy preterm and term infants at term‐equivalent age. The results showed that preterm infants have significantly lower RSA, and higher overall F 0 than term infants. Moreover, lower RSA was associated with higher overall F 0 in preterm infants, whereas higher RSA was positively associated with mean and maximum F 0, and a larger F 0 range in term infants. These results suggest that individual differences in vagal function may be associated with the F 0 of spontaneous cries via modulation of vocal fold tension in infants at an early developmental stage. © 2016 The Authors. Developmental Psychobiology Published by Wiley Periodicals, Inc. Dev Psychobiol 58:724–733, 2016.