Abstract: A continuous, non-invasive fetal heart rate measurement is produced using an ultrasound probe positioned on the abdomen of the mother. The ultrasound probe includes a plurality of ultrasound transducers that are positioned within a housing having a transmission surface. The transmission surface is configured to defocus the individual ultrasound beams created by the plurality of ultrasound transducers. The transmission surface defocuses the ultrasound beam and creates a wider area of coverage for the ultrasound probe. The controller contained within the heart rate monitor selectively activates different combinations of the plurality of ultrasound transducers to reduce the signal-to-noise ratio while allowing the ultrasound probe to locate the fetal heart beat and subsequently increase the signal-to-noise ratio during continuous heart rate monitoring.