Fetal Doppler


Pregnancy is an exciting and wondrous time for expectant mothers, and possibly one of the best moments a soon-to-be parent's experience is hearing the sound of their baby's heart beat for the first time. This is done through the use of a fetal doppler, and may be utilized as early as eight to twelve weeks into the pregnancy.

The Doppler Effect

Fetal doppler machines are non-evasive and use sound wave detection and measurement to emit the change in a sound waves pitch or frequency. This is done through the doppler effect, which is described as sending a short burst of sound towards the specific areas of the abdomen and then listening for the echo. The sound produced is not the actual heartbeat of the fetus, only a reproduction, and the fetal doppler does not harm the baby in any way.

Sounds Heard Through the Fetal Doppler

There are generally two types of fetal dopplers: regular and digital, and both may use a wand-like, non-evasive probe to pick up fetal heartbeats. A fetal heartbeat will generally run about 120-180 beats per minute, while the mother's heartbeat will usually, when at rest, run at about 60-100 beats per minute. So, the baby's heartbeat may sound very fast yet still be in the normal range, even at twice as fast as the mother! The probe will be able to pick up those sounds of the baby's heartbeat as well as perhaps the sounds of blood flow from the mother, which will make a swishing sound.

At times, a fetal doppler may also pick up some static sounds, similar to popping noises. This is why many physicians use a coupling agent known as ultrasound gel to reduce static. Ultrasound gel is made up of different components that normal gels and lotions do not possess, and using ordinary gels may actually increase the static noises and damage the probe. There are some surprising occasions, however, when what may appear to be static or the sound of a mother's blood is actually a second heartbeat signifying a multiple pregnancy! An experienced doctor or midwife should be able to detect multiple heartbeats, but the only true confirmation can come from an ultrasound, and not only through listening.

Home Use of Fetal Dopplers

Fetal dopplers are operated in a hospital or birthing center environment by a specially trained professional. However, there are fetal dopplers available for individual renting and purchase, including smaller, portable versions for home use. Obviously, under no circumstances should possessing a fetal doppler substitute for regular care and monitoring by a physician.

By Barbara Poelle           


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