A system and associated method include an AECG/PCG sensor configured to generate an AECG/PCG signal in response to a monitored fetal heart. The system also includes an US transducer configured to generate an US signal in response to the monitored fetal heart. The system also includes a computer configured to assess the quality of the AECG/PCG signal, and compare the assessed quality of the AECG/PCG signal with a selectable threshold value. The computer is also configured to disable the US transducer and process the AECG/PCG signal to provide a fetal heart rate estimate as long as the assessed quality of the AEC/PCG signal exceeds the selectable threshold value. The computer is also configured to enable the US transducer and process the US signal to provide a fetal heart rate estimate only if the assessed quality of the AEC/PCG signal is equal to or less than the selectable threshold value.