Spectral analysis of fetal heart rate variability as a predictor of intrapartum fetal distress

Objective: To evaluate the usefulness of power spectral analysis on fetal heart rate variability as a new diagnostic method of fetal distress. Study design: Among 76 pregnant women who underwent computerized electronic fetal monitoring and cord blood gas analysis, we divided them into three groups: normal fetus group (36); presumed distress group (26); and acidemic distress group (14). In order to perform linear analysis on the raw data of the fetal heart rate, after resampling, we performed Fourier transformation and investigated power distributions among very low frequency (VLF), low frequency (LF), high frequency (HF) bands, and autonomic balance (LF/HF). Results: The results of the spectral analysis showed that in normal fetus group, the difference in the distribution of power spectrums of VLF, LF and HF was significantly higher than in presumed distress group and acidemic distress group. In fetal distress, the LF and VLF value (less than or equal to0.0023, greater than or equal to 0.0437) were good predictors (sensitivity 97.5%, 75.0% and specificity 86.1%, 94.4%). The LF value (less than or equal to 0.0013) was a good predictor in fetal acidemia (sensitivity 97.5% and specificity 86.1%). Conclusions: A computerized spectral analysis of fetal heart rate variation is a good predictor of fetal distress, which is made automatically and objectively. (C) 2001 International Federation of Obstetrics and Gynecology. All rights reserved.