Fetal heartrate tracking system based on intensity of Doppler signal

Abstract

Doppler-detected fetal heart rate (FHR) tracking is the primary testing method for assessing fetal well-being during antepartum care. However, owing to fetal movements or maternal position variations, the transducer on the abdomen can be displaced, changing the fetal heart location (FHL) and resulting in frequent signal losses and uninterpretable results. In this study, we present FHR monitoring system for continuously maintaining FHR measurements without specifying the location of the Doppler ultrasound transducer. An algorithm is developed to track the FHL based on the intensity of the received Doppler signal. The performance is evaluated by conducting underwater experiments using an object with repeated movements. The tracking error is 7.93° on the X-axis and 1.42° on the Y-axis. Even with those tracking errors, the FHR is continuously recorded. This system can be used to obtain heart rate records without manipulating the position of the transducer and losing the signal.