Fetal heart rate (FHR) is an important indicator or biological index to know the condition of fetal well-being. This project leads to develop a fetal heart rate monitor that can be used by a pregnant mother in home environment. There are five steps taken to develop a fetal heart rate monitor: 1) data acquisition; 2) data pre-processing; 3) feeding into microcontroller; 4) postprocessing and 5) display. The condenser microphone was used as a sensor to acquire fetal heart sound data. The sensor acquires the data then undergoes pre-processing which involve amplification and filtration using fourth order low pass butterworth filter. The operational amplifier was used for pre-amplification during filteration; the operational amplifier used is LM 741. The signal acquires after pre-processing stage, sent to the microcontroller (ATMega328) for the computation and transmission of data by developing an algorithm so
that the computer can read the signal. Finally, the output (fetal heart rate) was displayed on LCD. In this preliminary study, the developed prototype was tested on 10 pregnant mothers supervised by specialised at the clinical set-up. The accuracy of the prototype fetal heart rate has been confirmed relative to electronic stethoscope. The overall bias for fetal heart rate based on relative verification between prototype and electronic stethoscope is 0.16 % and -0.14% respectively. Hence, the result shows that developed prototype can detect the fetal heart rate of maternal from third trimester onwards. In future the developed prototype device will be tested on larger database to confirm the accuracy of the device.