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

Objective: The aim of this study was to record, during labor, the brain stem auditory evoked potentials of the fetus from standard fetal scalp electrodes. Study Design: 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. Results: 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. Conclusion: 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. (Am J Obstet Gynecol 1999;180:1422-6.)