Think Twice Before Buying an At-Home Fetal Doppler - Consumer Reports (2024)

Every year, our access to data about our own bodies increases—data that is often obtained via devices we use at home. From fitness trackers, which monitor our daily movement, to sleep trackers, which attempt to record our sleep patterns, to fertility monitors, which estimate when we’re ovulating, our ability to obtain information about ourselves only grows.

Amid this expanding field of devices dwells the fetal doppler, a type of ultrasound that captures a fetus’s heart rate. Despite how high-tech it might seem to be able to use an ultrasound at home, fetal dopplers aren’t new—they’ve been in use for decades.

What Is a Fetal Doppler?

Fetal dopplers are a type of ultrasound machine that uses sound waves to “listen” to a baby’s heart. Dopplers reflect high-frequency sound waves—aka ultrasounds—off the blood to approximate the sound of blood flowing through the veins. “It’s an ultrasound that doesn’t have a picture,” says Tamika Alexander, MD, an obstetrician and an associate professor of clinical obstetrics and gynecology at the University of Illinois College of Medicine in Chicago.“Blood is going through the blood vessels and through the heart, and that’s what it’s picking up and that’s the sound that we hear.”

Dopplers are small handheld devices with a ’90s vibe: a small, often off-white plastic box with a simple screen and a wand, called a transducer, that the wielder drags over the belly in search of the baby’s heartbeat.

According to Joshua Copel, MD, a professor of obstetrics, gynecology, and reproductive sciences at Yale School of Medicine in New Haven, Conn., the device has two primary components (called “crystals”), one of which “is constantly sending out sound; the other is constantly listening to the returning sound. And the difference in the shifts causes the whoosh, whoosh, whoosh that you hear when you’re listening,” he says. “If it’s focused on the heart, it sounds like a galloping horse because the valves of the heart are moving. That’s the basic principles of how these devices work and why they’re so simple and inexpensive—because there’s not a lot of integrated circuitry or software that’s required.”

The fetal doppler your doctor uses is pretty much the same as the one you can buy online and use at home—so similar, in fact, that Alexander says that if her office ran out of them, they’d probably just order more on Amazon. But that doesn’t mean that you can use one at home as easily as a trained ultrasound technician, doctor, or nurse uses one in the doctor’s office.

Risks of Fetal Doppler—and Why You Should Avoid Using One at Home

The fetal doppler, at first sight, is a trifecta of ease. It’s easy to find online; it’s easy enough to put the ultrasound gel and the transducer to your abdomen; and it’s easy to understand why people would want to use these devices.

Pregnancy can feel terrifying. Especially in the early weeks, before you’re showing and perhaps before you’ve seen your doctor (in the U.S., you typically get in to see an obstetrician or a midwife around eight weeks into your pregnancy), it can be agonizing not to know exactly what is happening in there. Patients with normal pregnancies usually see their doctor or midwife once a month until week 28 or so; the wait between visits can be difficult and occasionally anxiety-inducing.

A fetal doppler can feel like a straightforward way to check in on the baby and make sure his or her heart is beating like it should. But its use is best left to the pros.

“It’s a bad idea” for patients to use a fetal doppler at home, says Priya Rajan, MD, an associate professor of maternal-fetal medicine and the medical director of diagnostic ultrasound at the Northwestern University Feinberg School of Medicine in Chicago.

Rajan’s trepidation comes from two angles: that patients will be falsely reassured by what they think is their baby’s heartbeat when the baby is, in fact, in danger; and that patients will not be able to hear their baby’s heartbeat and panic when everything is actually fine.

During the toughest days of the pandemic when prenatal visits were hard to secure, says Rajan, she had personal connections in her life ask her if she should use a fetal doppler at home. Rajan has tended to advise against it. “I felt like it was more likely to cause her anxiety because she was hearing something that was wrong, number one. Number two, I definitely didn’t want her to miss going to the hospital or the doctor when she needed to because she had falsely reassured herself,” she says. Plus, “there’s very little you can do based on what you hear on the doppler.” Even with Rajan providing information from afar, she isn’t comfortable with it, she says. “I knew the limitations of my remote guidance about what to do with that.”

Not to mention, while fetal dopplers appear on their face to be easy to use, the complexities of the human body mean they’re harder to wield correctly than you might think.

“Sometimes even in the clinic, I’ll struggle trying to get heartbeats on patients, and it has nothing to do with whether there’s something wrong with the baby,” Alexander says. The baby could be in a position that makes their heart difficult to find, or the uterus could be turned in a particular way, she says.

As difficult as it can be for the medical provider, it can be even harder for an untrained patient to use it on themselves at home. What sounds like your baby’s heartbeat could be your own, or it could be another blood vessel, or it could be the sloshing of the amniotic fluids. You can even pick up your own heartbeat alongside the baby’s, Alexander says, and think that you’re having twins that your medical providers somehow missed. It can cause a lot of extra anxiety during an already stressful time, she says. “Because [patients] haven’t actually been trained how to use the doppler, they can be picking up on things that someone who’s used the doppler regularly would not normally pick up on, or would know how to filter out.”

The Food and Drug Administration, for the record, cautions against home use of fetal dopplers, as does the United Kingdom Medicines and Healthcare Products Regulatory Agency, the British Medical Ultrasound Society, and the American Institute of Ultrasound in Medicine. Beyond the potential risk that patients will be incorrectly reassured or frightened by what their doppler hears (or doesn’t), there’s concern that excessive ultrasound use could expose fetuses to hazardous heat.

“The reason the FDA doesn’t like these devices is that there are at least theoretical risks of the energy used to create the sound, which is vibration, causing effects on the body—the mother or the baby,” Copel says. It’s a theoretical risk because “nobody has shown harm at the frequencies that are used,” he says. Still, the potential that the doppler could cause harm, combined with the lack of much benefit to its use, means it’s safer to save the heartbeat show for your next prenatal visit.

What to Do Instead

Want to keep tabs on your baby’s health while they’re still tucked away in the womb? If it’s later in pregnancy (at some point in the third trimester, according to the Cleveland Clinic), Alexander recommends paying attention to the baby’s movements, and not panicking if over the course of the workday you haven’t noticed much.

“Take a break and sit down and focus on it. Now, after sitting down and focusing on it, you still don’t feel the baby move, then you should come in and let us see you.” Most of the time, though, you’ll feel something, she says. It’s just easy to get distracted and not notice the occasional roll or kick when you’re focused on other things. Resorting to a doppler, on the other hand, could end up confusing and stressing you out more—and in the middle of pregnancy, when you’re nauseous and tired and maybe a little grumpy, more confusion and stress is the last thing you need.