How does a Fetal Doppler Work?
A fetal ultrasound Doppler is the most frequent method of monitoring a fetus. There are no known risks to the fetus and it is non-invasive. It is simple and very convenient to use. A fetal Doppler is most commonly used during each health care visit starting at 8 to 12 weeks of pregnancy. The Doppler gives the doctor a reliable range of the baby’s heart rate and helps them to determine any problems with the fetus.
The name Doppler comes from Austrian mathematician and physicist, Christian Doppler. He discovered the Doppler shift principle in 1842. Christian Doppler discovered that sound waves from a moving source would be compressed or expanded, or that the frequency would change. Fetal Doppler technology is based on this principle.
Fetal Dopplers work by sending and receiving ultrasound waves through the mother’s abdomen. When the waves are reflected from moving objects, such as the fetal heart, the frequency changes slightly. This change is then analyzed by the electronics inside the Doppler and converted into a sound that you can hear or a digital display of the heart rate.