Final answer:
To auscultate fetal heart rate, health professionals commonly use a Doppler ultrasound, which is preferred for its accuracy and non-invasive nature in detecting the fetal heart rate.
Step-by-step explanation:
The most commonly used tool to auscultate fetal heart rate is a Doppler ultrasound. Health professionals choose this method over others because it is non-invasive, safe, and provides accurate heart rate measurements. While a stethoscope is a fundamental auscultation tool for heart sounds, a fetoscope is a special stethoscope designed for fetal heart monitoring, and a blood pressure cuff is used along with a stethoscope for measuring blood pressure, they're not as efficient in detecting fetal heart rates as the Doppler ultrasound. The Doppler ultrasound works by emitting sound waves that reflect off moving objects, such as a beating heart. The shift in the frequency of these reflected waves, due to the Doppler effect, enables clinicians to determine the heart rate.