Fetal Dopplers: When Can You Use Them and How Do They Work?

A fetal Doppler is a type of tool your doctor will use during your prenatal care to assess your baby’s well-being. As an added bonus, you get to listen to your little bundle of joy’s beating heart.

Many moms-to-be also get at-home Dopplers to listen to their baby’s heartbeat whenever they please. However, medical experts caution against doing this.

Read on to find out what exactly fetal Dopplers are, when your doctor will use one, and why you should think twice about using one yourself.

In more detail, a fetal Doppler is a type of handheld ultrasound device (one that uses sound waves to create an image). Your doctor will use it to detect your baby’s heartbeat and evaluate his:

• Heart rate
• Heart rhythm

How do doctors use fetal Dopplers?

Here’s what you can expect when your doctor uses a fetal Doppler during one of your prenatal checkups:

1. You’ll undress from the waist down or simply pull your pants below your belly, then lie down on the exam table.
2. Your doctor will apply clear ultrasound gel to your lower abdomen.
3. They’ll press the Doppler probe against your abdomen and move it until they detect a heartbeat.
4. After listening for a few moments, your doctor will remove the probe and wipe off the gel.

Are fetal Dopplers safe?

Yes, fetal Dopplers are safe when a doctor or another qualified medical professional uses them during your prenatal checkups.

However, the same can’t necessarily be said for at-home fetal Dopplers. Although you can buy fetal Dopplers over the counter, most experts advise against doing so. It’s better to leave this job to the professionals.

Your doctor may use a fetal Doppler to check your baby’s heart rate and rhythm at your three-month checkup (i.e., when you’re 12 weeks pregnant) and repeat this at every prenatal visit thereafter.

In addition to using it during your prenatal visits, your doctor may also use a fetal Doppler to monitor your baby’s condition during labor, as reflected by his oxygen level. 1

For low-risk deliveries, periodic checks are usually enough. Your doctor may continuously monitor your baby’s heartbeat if they think your delivery is high-risk or as a part of routine protocol.

When can you hear your baby’s heartbeat with a fetal Doppler?

Usually, your baby’s heartbeat will start when you’re around 5 weeks to 6 weeks pregnant. 2

However, his heart won’t be fully developed until around week 10 of your pregnancy, and you probably won’t actually be able to hear it with a Doppler before you’re 12 weeks pregnant. 3

A fetal Doppler lets your doctor check your baby’s heart rate and rhythm, which enables them to assess his viability.

As well as making sure your baby is safe and healthy, a fetal Doppler lets you connect emotionally with him. Hearing your baby’s heart beating steadily will give you much-needed reassurance that he’s safe and  lay the foundation for your bond with him, which will last a lifetime.

Are fetal Dopplers ever inaccurate?

By and large, fetal Dopplers are very reliable when used by trained professionals. However, there’s a small chance that the monitor might suggest there’s a potential problem when none exists. This can lead to further (unnecessary) testing, and it might stress you out or scare you, but it won’t lead to any long-term problems.

Even if everything goes right, it can take a moment for your doctor to find your baby’s heartbeat, which could make you feel a little anxious. Any time you’re waiting for results related to your baby’s health, a few seconds can feel like an eternity. Be patient and stay calm while your doctor pokes around your belly.

While you can easily buy over-the-counter fetal Dopplers to listen to your baby’s heartbeat whenever you want at home, the US Food and Drug Administration (FDA) doesn’t recommend using them.

For starters, most at-home fetal Dopplers aren’t as sophisticated as the ones your doctor uses, which can make it challenging to correctly identify your baby’s heartbeat. You might mistake your own heartbeat or other sounds for your baby’s heartbeat. 4

Other reasons to avoid at-home Dopplers include: 4

• Lack of training: Unlike doctors and midwives, most parents don’t have training in interpreting fetal heart sounds. Without this, you could misinterpret the information. Hearing what you think is a clear heartbeat might provide false reassurance when problems that need treatment do, in fact, exist. Conversely, failing to find a heartbeat could cause you unnecessary panic.
• Unnecessary ultrasound exposure: Ultrasound waves can slightly heat your tissues and produce a little gas in your body fluids or tissues. While experts consider these risks low, they aren’t sure of the long-term consequences and suggest minimizing exposure to ultrasound waves. 4

The bottom line is that, although ultrasounds aren’t considered dangerous, as a matter of course, it’s best to minimize unnecessary medical procedures and only get them done by people with the requisite training.

That goes for any other at-home procedures you might be tempted to do in your pregnancy, too. Always run them by your doctor first to confirm that they’re really harmless.

Instead of relying on at-home Dopplers, you can monitor your baby’s health by counting his kicks. You should start regularly doing this when you’re around 28 weeks pregnant.

To do kick counts yourself:

1. Pick a time when your baby is usually active (after your biggest meal of the day tends to be best)
2. Time how long it takes for you to feel 10 movements (or kicks) with your watch or pregnancy tracker app
3. Repeat every day around the same time

Once you’ve been doing kick counts for a few days or weeks, you’ll start to get an idea of your baby’s movement patterns. If you notice a change in his movements, call your doctor right away. 5

How long should it take you to feel 10 kicks?

While experts are conflicted about how many movements you’ll need to feel within a given timeframe, the American College of Obstetricians and Gynecologists (ACOG) states that you should be able to feel 10 kicks within 2 hours. 6

However, rather than focusing on feeling 10 kicks within 2 hours, it’s more important to pay attention to your baby’s unique movement patterns. The best thing to do is get tailored advice from your doctor about how many kicks to look out for. If you don’t reach that number of kicks within the set timeframe, get medical attention immediately.

Other ways to keep your baby safe at home

Other than kick counting, the most important thing you can do for your baby’s well-being is attend all your prenatal appointments. There, your doctor will use fetal Dopplers and other professional devices to track your baby’s development and identify potential issues.

Lastly, remember to trust your maternal instincts. If you sense that something is wrong, don’t hesitate to contact your doctor.

While fetal Dopplers are the most common tool for monitoring your baby’s heart rate, there are other methods your doctor may use.

External fetal monitoring

Along with fetal Dopplers, your doctor can also use other forms of external fetal monitoring, such as: 1

• Stethoscope: Doctors sometimes use a traditional stethoscope further along in your pregnancy to monitor your baby’s heart rate.
• Fetoscope: This is a specialized stethoscope designed for listening to fetal heartbeats.
• Pinard horn: The pinard horn is also a type of stethoscope, although it has a simpler design than the fetoscope.
• Continuous Doppler monitoring: Your doctor may opt for continuous electronic fetal monitoring with a Doppler during labor and delivery to read your baby’s heart rate. Unlike with a handheld Doppler, your doctor will strap the device to your belly, along with a second strap and an instrument that measures your contractions. 7

Note that continuous external fetal monitoring usually isn’t necessary for low-risk pregnancies.

Internal fetal monitoring

If your doctor needs a more precise reading of your baby’s heart rate, they may perform internal fetal monitoring using an electronic transducer connected directly to his skin.

Also known as a spiral electrode, this electronic fetal heart rate monitor is more accurate and consistent than external methods. It works by being put through the cervical opening and attached to the baby’s skin (often on their scalp). 1

Note that your doctor can only use it after your water has broken. 7

Unfortunately, internal fetal monitoring presents far more risks to your baby than external methods, such as: 7

• Injuries to your baby’s scalp
• Transmission of HIV or genital herpes to your baby

Internal fetal monitoring is not recommended in women who have known HIV infections, and a vaginal delivery is also contraindicated in case of known active herpes.

There’s also a risk that you could get an infection as a result of internal fetal monitoring.

Although it’s tempting to listen to your baby’s heartbeat from the comfort of your own home, don’t use an over-the-counter fetal Doppler. It’s best to leave the device to professionals who know what they’re doing.

Stick to kick counting and trust your maternal instincts. You’ll get to hear that sweet thump-thump of your baby’s beating heart at your scheduled prenatal appointments.