ABSTRACT
OBJECTIVE: The purpose of this study was to evaluate the usefulness of approximate entropy on fetal heart rate variability of electronic fetal monitoring taken during antepartum and intrapartum periods as a new diagnostic method of fetal distress. METHODS: Among 76 pregnant women who underwent computerized electronic fetal monitoring and cord blood gas analysis, we divided them into 3 groups, i.e.; 36 into normal fetus group, 26 into presumed distress group and 14 into acidemic distress group. We performed a frequency analysis on time series of heart rate variability in three groups. In order to perform non-linear analysis on the raw data of the fetal heart rate, after resampling and low pass filtering, we investigated approximate entropy. RESULTS: The results of the approximate entropy showed that the value in normal fetus group was significantly high than the value in distress group. But in the distress group, ApEn value was not difference between acidemic and non-acidemic subgroup. ApEn of HRV was confirmed in nonlinear parameter without low pass filtering and resampling. CONCLUSION: The results show that the fetal heart rate variability has nonlinear characteristics and could distinguish normal fetal heart rate pattern and distress pattern numerically and objectively. And these ApEn value are useful for prediction and diagnosis of fetal distress in ante and prenatal periods.