A system (10) includes an AECG/PCG sensor (12) configured to generate an AECG/PCG signal (30) in response to a monitored fetal heart. The system (10) also includes an US transducer (14) configured to generate an US signal (32) in response to the monitored fetal heart. The system (10) also includes a computer (40) configured to assess the quality of the AECG/PCG signal (30), and compare the assessed quality of the AECG/PCG signal (30) with a selectable threshold value. The computer (40) is also configured to disable the US transducer (14) and process the AECG/PCG signal (30) to provide a fetal heart rate estimate as long as the assessed quality of the AEC/PCG signal (30) exceeds the selectable threshold value. The computer (40) is also configured to enable the US transducer (14) and process the US signal (32) to provide a fetal heart rate estimate only if the assessed quality of the AEC/PCG signal (32) is equal to or less than the selectable threshold value.
