The Fetal Doppler

In 1958, Dr. Edward H. Hon invented the Doppler Fetal Monitor or what we called Fetal Doppler a hand-held ultrasound transducer used to detect the fetal heartbeat for prenatal care. The doppler effect is used to provide an audible simulation of the heartbeat.

The work

Doppler work on the principle of listening to reflections of small, high frequency sound waves (ultrasound). These ultrasound waves are generated by microscopic vibrations of piezoelectric crystals. When the waves are reflected from moving objects, such as a fetal heart the frequency changes slightly.

The two types of Fetal DopplersSonoline B

(Sonoline B)

The Digital Doppler which allows you to hear the baby’s heartbeat and gives you a digital display of the baby’s heart rate per minutesonoline-a-250x250

(Sonoline A)

while Sound Doppler only allows you to hear the baby’s heartbeat.

The Buying Tips

  • Make sure that it is FDA approved and certified by Health Canada.
  • If you’re planning to get one online make sure you purchase at the official website of the doppler brand you choose and check if the company has provided an address and telephone number and offers a secure card processing.
  • Check carefully for the extras included in the price. You will need atleast 250ml of Ultrasound Gel (we recommend Aquasonic), most stockists don’t include gel and the ones that do usually provide a very small amount. Audio cables, earphones, warranty and support are all essentials.
  • Choose a product within budget and your own specific requirements.
  • Check on the warranty.
  • Always buy from a well trusted and recognised stockist.


Word of Advice

  • Remember that in the early stages of pregnancy the foetus is still quite small (approx 5cm at 12weeks) and so locating the heartbeat is not always easy
  • The fetal heart rate is usually between 140 to 160 beats per minute
  • The fetal heart sounds like a hoofbeats of a galloping horse
  • Use generous amount of Ultrasound Gel
  • Place the doppler probe low down on your abdomen
  • Tilt the doppler probe downwards towards the pelvic bone
  • Move the doppler probe VERY SOWLY until you pick up the heartbeat
  • A very easy way to find the heartbeat is to take your Doppler with you to your next prenatal appointment. Your OB or midwife can help you locate your baby’s heartbeat and provide you with helpful Doppler tips as well.


Note: Fetal Doppler should not be used in any way for diagnostic or medical purposes by anyone other than a medical professional and should not be used as a substitute for regular prenatal care by a medical practitioner. Any concerns about your pregnancy should be addressed to your health care provider.