Brain stem auditory evoked potentials in the human fetus during labor.

Abstract

The aim of this study was to record, during labor, the brain stem auditory evoked potentials of the fetus from standard fetal scalp electrodes. A personal computer-based instrument was developed to record, during labor, brain stem auditory evoked potentials from 10 fetuses ranging in gestational age from 36 to >/=40 weeks. Auditory stimulus was provided by clicks (16/s) delivered on the mother's abdomen with an intensity of 120 dB. The evoked potential signals were digitized and averaged. Interfering artifacts were excluded from the averages. In 80% of the subjects, all the principal waveforms of the brain stem auditory evoked potentials-waves I, III, and V-were clearly identifiable. The latency for wave I ranged from 1.2 to 2.2 ms, wave III from 3.4 to 5.6 ms, and wave V from 5.8 to 8.4 ms. The morphologic features of the waveform and the interwave latency values were similar to those of normal term infants recorded in the past studies. We have reestablished that it is possible to record auditory evoked potentials during labor from fetal scalp electrodes. Brain stem auditory evoked potentials may be a useful screening tool for at least the severely neurologically damaged fetus.