Neonatal Autonomic Function After Pregnancy Complications and Early Cardiovascular Development

BACKGROUND: Heart 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. METHODS: 98 sleeping neonates had 5-minute electrocardiogram recordings at birth. Standard time and frequency domain parameters were calculated and related to cardiovascular measures at birth and three 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), 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 term infants. However, differences in autonomic function did not predict cardiovascular measures at either time-point. 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 three months post birth. Long-term studies will be needed to understand relevance to cardiovascular risk.