Fetal Doppler

What Is a Fetal Doppler?

A fetal Doppler is a test that uses sound waves to check your baby’s heartbeat. It’s a type of ultrasound that uses a handheld device to detect changes in movement that are translated as sound.


How Early Will a Fetal Doppler Test Work?

Most women first hear their baby's heartbeat during a routine checkup that uses the fetal Doppler. Many ultrasound machines also allow the heartbeat to be heard even before it can be heard with a Doppler. Most women now get an ultrasound before 12 weeks.

A fetal Doppler test normally takes place during your second trimester (weeks 13 to 28 of pregnancy). Some manufacturers of at-home fetal Dopplers say you may be able to hear your baby’s heartbeat as early as 8-12 weeks of pregnancy. But professional sonographers say that they wouldn’t try to listen to a baby’s heartbeat before 13 weeks because your womb is in your pelvis during the first trimester and so the device won’t work correctly. Some at-home devices say not to use it before 16 weeks.

If you’re trying to hear your baby’s heartbeat at home, it may be best to first wait for your doctor to check it during one of your prenatal checkups. This is especially true if you’ve been pregnant for less than 12 weeks, to avoid undue concern. It’s a good idea to talk to your doctor first before buying an at home fetal Doppler. They can talk to you about the benefits and risks involved with using these devices.



How the Fetal Doppler Test Is Done

Clinical fetal Doppler test

If you go to your doctor’s office or clinic, you'll lie down and a technician will hold a small probe against your belly that makes sound waves. Technicians will ask you to stay still while this is going on. The sound waves will then be sent back to an amplifier where they can be heard. The procedure is safe and painless.

At-home fetal Doppler test

There are Dopplers that you can buy for use at home. But the FDA recommends parents not use these devices. There isn’t evidence that using them is harmful, but they haven’t been studied long term. The FDA notes that using them too much -- without medical supervision -- could pose risks to your baby’s development.

The bottom line is they should be used only if there is a medical need. The FDA does recognize that Dopplers can create bonding between parents and unborn babies, but it suggests parents can get this feeling from sessions in the doctor’s office.

Talk to your doctor before buying or using an at-home device.

Doing a fetal Doppler test at home may not run as smoothly as one done in your doctor’s office, either. You may need to watch some videos online to see how to do it correctly. At-home devices vary from brand to brand, so it’s important to read any instructions and recommendations that come with the packaging. Some mothers find it’s easier to find the heartbeat when they do the test with a full bladder.


Fetal Doppler Test Results

Hearing your baby's heartbeat for the first time can be deeply moving. Keep in mind that a baby's heartbeat is much faster than an adult's.

If you're in your first trimester and you can't hear your baby's heartbeat, don't worry. Dopplers can't reliably detect a baby's heartbeat until 10-12 weeks. Your doctor may try again on your next visit. An ultrasound may give you better results.

A fetal heart rate is between 110-160 beats per minute and can vary by 5-25 beats per minute. Your baby’s heart rate can change based on conditions in your uterus. If the heartbeat is outside of the range, it could mean that your baby isn’t getting enough oxygen or has another issue.

If your doctor is concerned about your baby’s heartbeat, they may recommend a fetal echocardiogram. This is a safe, noninvasive test and gives a detailed picture of your baby’s heart. It can help see if and what kind of irregular heartbeat (or arrhythmia) your baby may have so it can get the right treatment.



How Often Are Fetal Doppler Tests Done?

Your doctor may use the Doppler often to listen to your baby's heartbeat during routine checkups, starting at about 8-10 weeks. Handheld Dopplers won’t work this early.

How often fetal Doppler tests are done can vary, but they may be part of routine second trimester checkups. Your doctor may even use them to monitor your baby’s heartbeat during labor and birth.

Difference Between Fetal Doppler and Ultrasound

Parents who use a fetal Doppler at home may not get as good results as they do from the ultrasound in the doctor’s office. For one thing, if you use it too early or place it in an incorrect position, you might hear no heartbeat and worry. Or you might hear a heartbeat (possibly your own or your pulse) and think everything is OK when it’s not. Also, the at-home fetal Doppler mainly picks up a baby’s heartbeat (although some companies are offering 3D and 4D ultrasounds, which allow you to see pictures and videos of your fetus.)

The most common medical ultrasound is the transvaginal ultrasound, where a wand (called a transducer) is placed in your vagina to send out sound waves and gather information. Another popular ultrasound, the transabdominal ultrasound, is done by moving the device over your stomach, similar to what you do in an at-home Doppler.

Professional ultrasounds are used for a variety of things. Ultrasound may confirm your pregnancy, determine how long you've been pregnant, hear a baby's heartbeat, as well as check for any abnormalities in your baby. It can also determine placenta and amniotic fluid levels and even what position your baby may be born in. A professional fetal Doppler can give details about a baby's blood flow.

WebMD Medical Reference Reviewed by Hansa D. Bhargava, MD on July 01, 2020



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SSM Health Cardinal Glennon Children’s Hospital: “Fetal Arrhythmia.”

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