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Low human fetal heart rate variation in normal pregnancy
Author(s) -
SMITH J. H.,
DAWES G. S.,
REDMAN C. W. G.
Publication year - 1987
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.1471-0528.1987.tb03170.x
Subject(s) - fetus , medicine , heart rate , gestation , fetal heart rate , pregnancy , gestational age , obstetrics , cardiology , biology , blood pressure , genetics
Summary The fetal heart rates of 340 normal singleton pregnancies at 30–33 weeks gestation were screened using a microprocessor system on‐line. Eleven fetuses (3·2%) with a heart rate variation less than the 5th centile were identified, of whom 10 were studied longitudinally. At 30–33 weeks the mean minute range of pulse intervals (a measure of fetal heart rate variation) was 314 (SE 1·5) ms compared with 51·0 (SE 3·4) ms in a randomly selected control group. The study group continued to have significantly lower fetal heart rate variation than controls on each of three subsequent occasions until delivery. There were no significant differences between the two groups in fetal outcome, which was good. This demonstrates that a small proportion of normal fetuses have consistently low heart rate variation, and helps to define the lower limit of the normal distribution of fetal heart rate variation. After delivery, there were no significant differences between heart rate or its variation between the two groups. We conclude that the lower prenatal heart rate variation in the study group was a consequence of the uterine environment.