A passive DSP approach to fetal movement detection for monitoring fetal health

Fetal movement can help clinicians understand fetal functional development. Active methods for fetal monitoring such as ultrasound are expensive and there are objections to their long term usage. This paper presents a passive approach for fetal monitoring which uses solid state accelerometers placed on the mother´s abdomen for the collection of fetal movements. The proposed fetal movement detection is based on the root-mean-square (RMS) of time series. The detection performance is evaluated against real-time ultrasound imaging. A good detection rate of 80% and a positive predictive value of 77% were achieved based on the analysis of 4 subjects. Time-frequency (TF) analysis of fetal movement signals, using a number of quadratic TF distributions, has shown that some fetal movements are spectrally characterized by nonstationary and nonlinear behavior and that fetal activity is generally below 20 Hz. More data are needed for further TF analysis and future detections will depend on the outcome of this analysis.