A method of monitoring a fetal heart rate, the method comprising: detecting average fetal heart rate across an ultrasound depth zone of sensitivity as a reference FHR; scanning at least the ultrasound depth zone of sensitivity in overlapping increments of a first depth; calculating a signal quality for each overlapping increment; determining an FHR waveform at each overlapping increment; determining an average increment FHR for each overlapping increment from the FHR waveform at each overlapping increment; determining a coincidence between the average increment FHR and the reference FHR across the ultrasound depth zone of sensitivity; determining an FHR waveform stability at each overlapping increment; identifying adjacent overlapping increments with a maximized signal quality; operating an ultrasound probe across an ultrasound depth increment of a second depth representing the adjacent overlapping increments to produce a returned ultrasound signal; determining FHR from the returned ultrasound signal; and the method further comprising the following steps performed by a processor: verifying that the identified adjacent overlapping increments with the maximized signal quality have stable FHR waveforms and the average increment FHR is coincident to the detected reference FHR; wherein if the identified adjacent overlapping increments with the maximized signal quality have stable FHR waveforms and the average increment FHR is coincident to the detected reference FHR, then the ultrasound depth increment of the second depth is selected, and if the identified adjacent overlapping increments with the maximized signal quality do not have a stable FHR waveform or the average increment FHR is not coincident to the detected reference FHR, producing an alarm indicating a possible maternal artifact. detecting average fetal heart rate across an ultrasound depth zone of sensitivity as a reference FHR; scanning at least the ultrasound depth zone of sensitivity in overlapping increments of a first depth; calculating a signal quality for each overlapping increment; determining an FHR waveform at each overlapping increment; determining an average increment FHR for each overlapping increment from the FHR waveform at each overlapping increment; determining a coincidence between the average increment FHR and the reference FHR across the ultrasound depth zone of sensitivity; determining an FHR waveform stability at each overlapping increment; identifying adjacent overlapping increments with a maximized signal quality; operating an ultrasound probe across an ultrasound depth increment of a second depth representing the adjacent overlapping increments to produce a returned ultrasound signal; determining FHR from the returned ultrasound signal; and the method further comprising the following steps performed by a processor: verifying that the identified adjacent overlapping increments with the maximized signal quality have stable FHR waveforms and the average increment FHR is coincident to the detected reference FHR; wherein if the identified adjacent overlapping increments with the maximized signal quality have stable FHR waveforms and the average increment FHR is coincident to the detected reference FHR, then the ultrasound depth increment of the second depth is selected, and if the identified adjacent overlapping increments with the maximized signal quality do not have a stable FHR waveform or the average increment FHR is not coincident to the detected reference FHR, producing an alarm indicating a possible maternal artifact.