The aim of this study was to investigate cardiovascular autonomic balance in normal pregnancy through spectral analysis of heart rate variability. For this purpose, electrocardiograms were recorded in 8 nonpregnant women and in 32 pregnant women at 10-39 weeks of gestation. Low- /high-frequency peak (LF/HF) ratio was used as an indirect index of sympathovagal balance. In left lateral recumbency, the LF/HF ratio was lower in pregnant women than in control subjects at all gestational ages. The LF/HF ratio was not affected by turning from left lateral to supine recumbency in control subjects, whereas it significantly increased in pregnant women (eg, from a mean +/- SD of 1.05 +/- 0.81 to 2.18 +/- 1.69 after the 33rd week of gestation). Handgrip at low intensity remarkably increased the LF/HF ratio both in control subjects (from 2.21 +/- 2.76 to 2.73 +/- 1.91) and in pregnant women (from 1.28 +/- 1.17 to 2.24 +/- 0.95 at 34-39 weeks of gestation). The results suggest that a rearrangement of autonomic tone takes place in normal pregnancy, which could be interpreted either as a shift of autonomic balance toward a relative vagal predominance or as the consequence of attenuation of baroreflexes.
Autonomic changes during pregnancy: Assessment by spectral heart rate variability analysis
VERLATO, Giuseppe;
1998-01-01
Abstract
The aim of this study was to investigate cardiovascular autonomic balance in normal pregnancy through spectral analysis of heart rate variability. For this purpose, electrocardiograms were recorded in 8 nonpregnant women and in 32 pregnant women at 10-39 weeks of gestation. Low- /high-frequency peak (LF/HF) ratio was used as an indirect index of sympathovagal balance. In left lateral recumbency, the LF/HF ratio was lower in pregnant women than in control subjects at all gestational ages. The LF/HF ratio was not affected by turning from left lateral to supine recumbency in control subjects, whereas it significantly increased in pregnant women (eg, from a mean +/- SD of 1.05 +/- 0.81 to 2.18 +/- 1.69 after the 33rd week of gestation). Handgrip at low intensity remarkably increased the LF/HF ratio both in control subjects (from 2.21 +/- 2.76 to 2.73 +/- 1.91) and in pregnant women (from 1.28 +/- 1.17 to 2.24 +/- 0.95 at 34-39 weeks of gestation). The results suggest that a rearrangement of autonomic tone takes place in normal pregnancy, which could be interpreted either as a shift of autonomic balance toward a relative vagal predominance or as the consequence of attenuation of baroreflexes.
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