title: Autonomic changes during pregnancy: assessment by spectral heart rate variability analysis.
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.
authors.affiliation: Centro Materiali e Biofisica Medica, Povo, Trento, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Speranza
authors.forename: G
authors.initials: G
authors.lastname: Verlato
authors.forename: A
authors.initials: A
authors.lastname: Albiero
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology; D001341:Autonomic Nervous System / Q000502:physiology*; D004562:Electrocardiography; D005260:Female; D005865:Gestational Age; D006321:Heart / Q000294:innervation; D006339:Heart Rate / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy / Q000502:physiology*; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D013564:Sympathetic Nervous System / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology