IngentaConnect Marked fetal acidosis and specific changes in power spectrum anal...

Authors: Siira, Saila M.¹; Ojala, Tiina H.²; Vahlberg, Tero J.³; Jalonen, Jarmo O.¹; Välimäki, Ilkka A.²; Rosén, Karl G.⁴; Ekholm, Eeva M.⁵

Source: BJOG: An International Journal of Obstetrics & Gynaecology, Volume 112, Number 4, April 2005 , pp. 418-423(6)

Publisher: Blackwell Publishing

Abstract:

Objective

To assess whether intrapartum acidosis affects specific components of fetal heart rate variability. Design

Prospective clinical study. Setting

Twelve Nordic delivery units. Subjects

Fetal heart rate variability was studied in 334 fetuses divided into two groups according to cord pH value: the acidotic group (cord arterial pH <7.05 at birth, n= 15) and the control group (cord arterial pH ≥7.05 at birth, n= 319). Methods

In spectral analysis of fetal heart rate variability, frequencies were integrated over the total frequency band (0.04–1.0 Hz), low-frequency band (0.04–0.15 Hz) and high-frequency band (0.15–1.0 Hz). We also calculated the low-to-high frequency ratio. Main outcome measures

The spectral bands of fetal heart rate variability were compared between the acidotic and control fetuses. Results

We found that during the last hour of monitoring, baseline fetal heart rate gradually decreased, whereas total, low-frequency and high-frequency fetal heart rate variability initially increased but then, near the delivery, decreased in the acidotic fetuses when compared with the controls. Low-to-high frequency ratio was greater in the acidotic group during the whole study period (P= 0.002). Cord artery pH was inversely associated with total fetal heart rate variability (P < 0.001), low-frequency fetal heart rate variability (P < 0.001) and low-to-high frequency ratio (P= 0.004). Conclusions

Marked fetal acidosis was associated with frequency-specific changes in fetal heart rate variability as reflecting the compensation ability of autonomic nervous activation during the last hour of labour.

Document Type: Research article

DOI: 10.1111/j.1471-0528.2004.00454.x

Affiliations: 1: Research Centre of Applied and Preventive Cardiovascular Medicine (CAPC), University of Turku, Finland 2: Department of Paediatrics, University of Turku, Finland 3: Department of Biostatistics, University of Turku, Finland 4: Perinatal Centre, Department of Physiology, University of Gothenburg, Sweden 5: Department of Obstetrics and Gynaecology, University of Turku, Finland

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Marked fetal acidosis and specific changes in power spectrum analysis of fetal heart rate variability recorded during the last hour of labour