The ratio of the low frequency to high frequency components in HRV power spectrum(LF/HF) fluctuates with the change in the sleep stages.

HRV频谱中低频和高频成分的比值（LF/HF）随着睡眠深度的变化而波动。

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Conclusions Relative changes in LF/HF ratio of FHR variability in relation to a significant ST-event are more pronounced in fetuses born with metabolic acidosis.

结论：S T改变相关的胎心率低高频比值变异能更好的反应新生儿代谢性酸中毒。

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