Heart rate cyclicity during labor in healthy term fetuses.
Fifty-four intrapartum fetal heart rate (FHR) tracing were subjected to retrospective analysis of the presence, length, and frequency of cyclic changes in long-term variability (cyclicity). All patients had spontaneous uncomplicated labor and received no narcotics or analgesics. The following cycles were identified according the difference in long-term variability in terms of amplitude range: cycle A, 0 to 2.5 beats/min; cycle B, 3 to 5 beats/min; cycle C, 6 to 10 beats/min; and cycle D, 11 to 20 beats/min. The frequency and length of FHR cycles was established in the latent, active phases and second stage of labor. Periods of diminished variability should be followed by fetal acid-base assessment only if their duration exceeds the established norms.
Petrikovsky
B M
BM
Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington 06032.
Vintzileos
A M
AM
Nochimson
D J
DJ
D005260:Female; D005323:Fetal Monitoring; D006340:Heart Rate, Fetal; D006801:Humans; D007743:Labor, Obstetric; D011247:Pregnancy; D012189:Retrospective Studies