Intrapartum computerized fetal heart rate parameters and metabolic acidosis at birth.
OBJECTIVE
To estimate to what extent computerized fetal heart rate (FHR) parameters are affected by labor and to estimate the relationship between FHR parameters and the degree of fetal metabolic acidosis in laboring patients at term.


METHODS
Fifty-one women between 37 and 42 weeks' gestational age were recruited prospectively in the following groups: 1) nonlaboring women, and 2) laboring women requiring fetal scalp electrode for continuous electronic FHR monitoring. Computerized FHR analysis was performed for 1 hour within 6 hours of delivery in the nonlaboring group and continuously throughout labor in the laboring group. Multiple linear regression analysis was used to determine the relationship between individual FHR parameters during the last hour before delivery and the degree of metabolic acidosis at birth.


RESULTS
The umbilical cord artery base excess and pH did not show any significant correlation with any of the computer-derived FHR parameters studied. Both umbilical cord venous base excess and pH were inversely related to the number of large FHR decelerations (r = -.46, P <.01 and r = -.56, P <.01, respectively). Labor was associated with a 31% increase in both short- and long-term FHR variation in the reassuring FHR tracing group when compared with nonlaboring women. Although this increase in FHR variation was not seen in the nonreassuring FHR tracing group, there was no relationship to the degree of metabolic acidosis at birth.


CONCLUSIONS
In term pregnant women with reassuring FHR tracing, labor causes an increase in both short- and long-term FHR variation, which was abolished in the presence of nonreassuring FHR tracing. Computer-derived FHR parameters studied during the last hour of labor were not correlated with the degree of metabolic acidosis as measured in the umbilical artery at birth.
Agrawal
Sumit K
SK
Department of Obstetrics and Gynaecology, University of Western Ontario, London, Ontario, Canada.
Doucette
Fred
F
Gratton
Robert
R
Richardson
Bryan
B
Gagnon
Robert
R
D000138:Acidosis / Q000175:diagnosis* / Q000503:physiopathology; D000328:Adult; D001784:Blood Gas Analysis; D015331:Cohort Studies; D003936:Diagnosis, Computer-Assisted / Q000379:methods / Q000592:standards; D005260:Female; D005312:Fetal Blood; D005316:Fetal Distress / Q000175:diagnosis* / Q000503:physiopathology; D005323:Fetal Monitoring / Q000379:methods / Q000592:standards*; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D007743:Labor, Obstetric; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D014469:Umbilical Arteries; D014471:Umbilical Veins