Abstract
Introduction: Beneficial effects of antenatal glucocorticoid treatment in pregnancies at risk for preterm delivery may entail long-term consequences for the establishment of sympathoadrenergic system balance. We analyzed the cardiac autonomic system activity in neonates with a single course of antenatal betamethasone (2×12mg) treatment. Methods: Time-domain and frequency-domain parameters for heart rate variability (HRV) were analyzed from 24h ECG recordings in 23 treated neonates and compared to 23 controls. Resting and challenged salivary α-amylase levels were measured in exposed neonates and controls. Results: Indicators for overall HRV (SD of all valid NN intervals: P=0.258; triangular index: P=0.179) and sympatho-vagal balance (low frequency/high frequency (HF) P=0.553) were not significantly different in the treatment group. Parameters mostly influenced by sympathetic activity (SD of the average of valid NN intervals: P=0.182; average of the hourly means of SDs of all NN intervals: P=0.78) as well as by vagal tone (average of the hourly square root of the mean of the sum of the squares of differences between adjacent NN intervals: P=1.0; proportion of pairs of adjacent NN intervals differing by 50ms: P=0.852; HF: P=0.921) were unaltered. Resting α-amylase levels were not significantly different in the treatment group (P=0.304), however, α-amylase release after a neonatal challenge was slightly reduced (P=0.045). Conclusion: Cardiac autonomic balance seems to be preserved in neonates exposed to a single course of antenatal betamethasone treatment. Putative long-term effects of antenatal steroids seem not to be originated from intrauterine induced cardiac sympathetic system alterations.
Published Version
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