To calculate your unborn baby’s fetal heart rate, simply count the beats you hear for 15 seconds and multiply that number by 4. This will give you an average of your baby’s beats per minute.
The best way to begin an exam is to by lying down exposing the abdomen. Apply a generous amount of ultrasound gel to the probe.
Early in pregnancy, it’s best to begin with the probe on the midline of the abdomen (above the pubic line) aiming downward behind the pubic bone. The probe should then be angled slowly in search for the fetal heart rate.
Be patient. Early in pregnancy, the size of the fetal heart is so small and the sound so faint that it can be very easy to pass over and miss the sounds.
In some women the fetal heart can be heard as early as 8 to 12 weeks.
While FDA regulates ultrasound and has cleared it for “continuous use,” it is suggested that you use your fetal Doppler in short intervals, infrequently, and following the first trimester.