Spectral analysis of fetal heart rate variability associated with fetal acidosis and base deficit values

The physiological response during fetal distress caused by labor varies from case to case and it is reflected both in the umbilical cord pH value and the fetal cord arterial base deficit (BDecf). The purpose of this study is to reveals the changes in fetal heart rate variability in abnormal cases (pH <; 7.2 and BDecf > 8 mmol/L). Fetal heart rate variability (fHRV) was computed in 289 records with both normal and abnormal fetal outcome. The records were divided into two groups, the control group and the test group. Next we computed the Fast Fourier Transform for each group to obtain the spectra for low, mid, and high frequency bands. We have used the normalized values of the mid and high frequency bands and the mid and high frequency ratio. We applied a t-test to divide the test group into two classes, and the pH and BDecf values were used to validate the results. Finally, we obtained a sensitivity of 96% and a specificity of 87.6%. The Spearman correlation coefficients and the scatter matrix also point to a very strong relationship between the fHRV metrics and the three outcome parameters: pH, BDecf, and Apgar scores.