A real time algorithm for the portable recording of fetal and maternal heart rates

A PIC17C44 microcontroller development board and a real-time algorithm were developed with the capability of monitoring the fetal heart rate (FHR) as well as recording both the FHR and maternal heart rate (MHR) for 24 hours. This paper describes the implementation of the real time algorithm by using the development board which is used to develop the portable recorder. The signal processing algorithm processes the abdominal electrocardiogram (AECG) signal which is sensed via a single pair of electrodes and continuously detect both the fetal and maternal QRS complexes for the measurement of the heart rates. The algorithm detects the MECG complexes and removes these from the AECG signal for enhancing the fetal QRS complexes. The average performance of the algorithm is 70%. It is based upon digital analysis of slope, amplitude and width of the signal. It automatically adjusts thresholds and parameters to adapt to such ECG changes as the QRS morphology and heart rates. The results acquired by the developed algorithm are also included.