Consultant neonatologist Monash University, Monash Children's Hospital Melbourne, Victoria, Australia
Background: Fetal growth restriction (FGR) is a major cause of preterm delivery. Preterm FGR infants often endure prolonged hospital stay with increased morbidities including cardiovascular complications, compared to preterm infants with weight appropriate for gestational age (AGA). Skin-to-skin care (SSC) is recommended by the WHO as routine care for low birth weight infants. SSC provides multiple physiological benefits in preterm infants including improved cardiac function and autonomic regulation. However, the effect of SSC on autonomic cardiovascular control in preterm FGR infants remains unknown. Objective: We aimed to assess the effects of SSC on cardiovascular control using heart rate variability (HRV) in preterm FGR compared to AGA infants. Design/Methods: Continuous electrocardiogram (ECG) was recorded from bedside monitors in 42 preterm infants born at median (range) gestational age of 29.7 (25-32) weeks, for 30 mins before and 60 mins during SCC. The FGR group (n=22) had higher birth weight z-score [median (IQR)] than the AGA group (n=20) [-1.59 (-2.03,-1.30) vs 0.04 (-0.49, 0.75), p< 0.0001). Spectral analysis was performed on R-R interval series in a low frequency band (LF, 0.04-0.15 Hz, related to sympathetic + parasympathetic changes) and a high frequency band (HF, 0.4-1.5 Hz, related to respiratory and parasympathetic modulation). HRV LF and HF power and LF/HF were calculated in moving 2-min windows updated every 10 sec. Periods of acute heart rate decelerations and movement artefacts were excluded from the analyses. Comparison was made between FGA and AGA infants; and also between infants with baseline (pre-SSC) HRV above and below the median in each group, using unpaired t-test or Mann-Whitney for parametric or non-parametric data respectively. Results: No overall change in HRV was noted during SSC for the entire group, FGR or AGA groups compared to the baselines. For the entire group, infants with low baseline HRV LF below the median had increased HRV during SSC (p=0.02, Fig 1A) and a similar trend was observed for HRV HF (p=0.07, Fig 1C). In contrast, infants with high baseline SSC HRV above the median had decreased HRV during SSC (p=0.02 for LF, p=0.03 for HF, Fig 1B&D). For the FGR group, those with low baseline HRV LF had increased HRV (p=0.05, Fig 1A). In the AGA group, no HRV difference was found during SSC for infants with high or low baseline HRV.
Conclusion(s): Infants with low baseline HRV suggesting reduced autonomic control are more likely to benefit from skin-to-skin care and increase their HRV, and this effect is stronger in FGR than AGA infants.
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