Abstract
BackgroundHeart rate variability (HRV) has emerged as a predictor of later cardiac risk. This study tested whether pregnancy complications that may have long-term offspring cardiac sequelae are associated with differences in HRV at birth, and whether these HRV differences identify abnormal cardiovascular development in the postnatal period.MethodsNinety-eight sleeping neonates had 5-min electrocardiogram recordings at birth. Standard time and frequency domain parameters were calculated and related to cardiovascular measures at birth and 3 months of age.ResultsIncreasing prematurity, but not maternal hypertension or growth restriction, was associated with decreased HRV at birth, as demonstrated by a lower root mean square of the difference between adjacent NN intervals (rMSSD) and low (LF) and high-frequency power (HF), with decreasing gestational age (p < 0.001, p = 0.009 and p = 0.007, respectively). We also demonstrated a relative imbalance between sympathetic and parasympathetic tone, compared to the term infants. However, differences in autonomic function did not predict cardiovascular measures at either time point.ConclusionsAltered cardiac autonomic function at birth relates to prematurity rather than other pregnancy complications and does not predict cardiovascular developmental patterns during the first 3 months post birth. Long-term studies will be needed to understand the relevance to cardiovascular risk.
Highlights
Heart rate variability (HRV) analysis provides a non-invasive measure of cardiac autonomic function, based on variation in the QRS to QRS (RR or normal to normal (NN) interval) interval sequence of the electrocardiogram (ECG)
Study population characteristics The technology for assessment of HRV became available during the course of recruitment to the EPOCH study, and, out of the 266 infants in the full neonatal cohort, 140 infants had an ECG taken at birth
There was a positive association between standard deviation of the NN intervals (SDNN), rMSSD, LF and highfrequency power (HF), and gestational age at birth, the association with SDNN failed to reach significance after adjusting for postnatal age at assessment and offspring sex (Table 2)
Summary
This study tested whether pregnancy complications that may have long-term offspring cardiac sequelae are associated with differences in HRV at birth, and whether these HRV differences identify abnormal cardiovascular development in the postnatal period. Standard time and frequency domain parameters were calculated and related to cardiovascular measures at birth and 3 months of age. RESULTS: Increasing prematurity, but not maternal hypertension or growth restriction, was associated with decreased HRV at birth, as demonstrated by a lower root mean square of the difference between adjacent NN intervals (rMSSD) and low (LF) and highfrequency power (HF), with decreasing gestational age (p < 0.001, p = 0.009 and p = 0.007, respectively). CONCLUSIONS: Altered cardiac autonomic function at birth relates to prematurity rather than other pregnancy complications and does not predict cardiovascular developmental patterns during the first 3 months post birth.
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