title: A longitudinal description of heart rate variability in 28--34-week-old preterm infants.
abstract: The purpose of this study was to longitudinally describe changes in heart rate variability (HRV) from 28 to 34 weeks postmenstrual age (PMA). A convenience sample of 31 low-risk preterm infants participated. HRV was quantified using a spectral analysis of heart periods and recorded during seven weekly test sessions from an electrocardiogram (ECG) signal. The total range of frequency components (0.04-2.0 Hz), high-frequency (HF) components (0.30-1.3 Hz), and ratio of low-to-high frequency (LF/HF) components (0.04-0.20/ 0.30-1.3 Hz) were measured. A mixed general linear model analysis revealed no significant change over weekly test sessions for the total, the high, and the ratio of LF/HF components. A significant interaction effect was, however, noted in the HF components for test session x gender (df = 1; F = 4.85; p = .030). With increasing age, the HF components for females increased or displayed a pattern of HRV indicative of a more mature autonomic nervous system (ANS). Study findings warrant further investigation of the impact of gender on normative descriptions of HRV.
authors.affiliation: College of Nursing, University of Florida, Health Science Center, Gainesville, FL 32610, USA. ckrueger@ufl.edu
authors.forename: Charlene
authors.initials: C
authors.lastname: Krueger
authors.forename: JoHannes H
authors.initials: JH
authors.lastname: van Oostrom
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shuster
mesh_terms: D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008137:Longitudinal Studies; D008297:Male