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PATTERNS OF FETAL HEART RATE DURING NORMAL PREGNANCY
Author(s) -
Wheeler T.,
Murrills A.
Publication year - 1978
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1978.tb15819.x
Subject(s) - gestation , heart rate , fetus , bradycardia , medicine , tachycardia , fetal heart rate , cardiology , beat (acoustics) , heart rate variability , pregnancy , blood pressure , biology , genetics , physics , acoustics
Summary Ninety‐seven recordings of the fetal heart rate, lasting for one hour, were made from 59 normal patients between 21 and 41 weeks of gestation. The heart rate was measured from beat to beat using the R‐wave of the fetal electrocardiogram (ECG) as the indicator of each heart cycle. The recordings showed a significant decrease in the baseline heart rate as gestation advanced. Significant departures from the baseline took the form of short episodes of bradycardia in the earlier recordings and short episodes of tachycardia in the later recordings. The undulatory pattern of variability was most common (46 per cent of the recording time); the proportion of narrowed undulatory variability decreased significantly and the proportion of saltatory variability increased significantly as gestation advanced. From 34 weeks of gestation, long‐term changes in the pattern of the fetal heart rate, related to periods of fetal rest and activity, were observed in the recordings. The periods of rest lasted for an average of 15 minutes and were characterized by a reduction in heart rate variability to the narrowed undulatory and silent types. Analysis of the cardiac beat‐to‐beat variation showed an arrhythmia, not previously described in the human fetus, that may be related to fetal breathing.