By Kate DaleyUpdated Oct 02, 2019
When you’re pregnant, it’s natural to want to know what’s happening inside your growing belly. With the advent of many new pregnancy monitoring devices, it’s easier (and more tempting) than ever to check in on your baby’s health at home. But are these machines safe and reliable? We asked the medical experts to tell us the benefits and risks of using an at-home fetal Doppler.
Fetal Doppler heartbeat monitors work just like the ultrasound technology used in your doctor’s office, but they have a lower intensity, explains Ori Nevo, an obstetrician who specializes in high-risk pregnancy care and co-director of the Toronto Centre for Early Fetal Ultrasound at Sunnybrook Health Sciences Centre. These types of heartbeat ultrasounds also don’t produce images; instead, they pick up the sound of your baby’s heartbeat.
A fetal Doppler sends out a beam of high-frequency sound waves that reflect off various tissues, explains Kenneth Lim, division head of maternal fetal medicine at BC Women’s Hospital and Health Centre. If the device detects a beating heart, it converts it to an auditory signal.
There are a few reasons why you should proceed with caution with these handheld devices.
Ultrasound can heat tissues slightly and, in some cases, produce very small bubbles in tissue, according to experts at the United States Food and Drug Administration (FDA). Lim and Nevo agree that there are thermal risks, as well as the potential to aggravate fetal tissue. “If you hold it in one place for a very long time, it can heat the tissue at some point,” explains Nevo. While ultrasound is considered to be quite safe in the hands of a technician, if a person doesn’t know what they are doing (such as listening to the heartbeat excessively by keeping the transducer in one spot), it has the theoretical potential to affect the fetus. Keep in mind that there are theoretical risks for any kind of ultrasound, including a home fetal Doppler, says Lim, because it transmits energy to the fetus, which has “the theoretical potential to cause harm if excessive energy is transmitted.” While there’s no definitive evidence that ultrasound can cause harm, some studies show that it could have effects on brain development, so it should be used sparingly. Many people feel it’s not worth the risk if it’s not medically required.
One of the main issues with using an at-home fetal Doppler is that you might not be able to find the baby’s heart rate easily. “The beam must be aligned with the heart,” says Lim. “Otherwise, you won’t hear anything. As you can imagine, not finding a heartbeat or misinterpreting a signal may generate anxiety and panic.” Also, because there is no quality control with many of these commercial products, it might take longer to find a heartbeat, which can lead to excessive ultrasound exposure for your baby. Doctors aren’t sure what the implications are because every device is different, but any ultrasound could affect your baby, especially if it’s placed in one spot for too long.
If there are concerns about the health of a fetus, there’s always a risk that an expectant mother could detect her own heartbeat while using the device and be falsely reassured that everything is OK. “The beam picks up any movement—not just the fetal heart but maternal blood vessels and any other movement,” explains Lim. Also, most people won’t be able to recognize if their baby’s heart rate is too slow or too fast, which could lead to a delay in seeking medical help.
“I am unaware of any proven medical benefits for using this device at home,” says Lim, noting that he would only advise home use under the direction of a medical professional. “For some couples, the only benefit is to reduce extreme anxiety, but that would be in very rare circumstances,” says Lim. “I’ve had to prescribe it for home use a couple of times over the past 10 to 15 years, and those were for uncommon medical situations.”
“I've seen patients with a history of pregnancy complications who want to make sure that the baby is developing properly and there’s a normal heart rate,” says Nevo. “I’m not sure why some people use it because once you feel the baby moving, you don’t need to listen to the heartbeat.”
A fetus should not be exposed to ultrasound for commercial or entertainment purposes, according to a joint statement released by the Canadian Association of Radiologists and the Society of Obstetricians and Gynaecologists of Canada in February 2014. Health Canada and the FDA also strongly advise against the use of ultrasound scans for entertainment and recommend that they are only performed by professionals.
“We just suggest monitoring baby movement,” says Nevo. After about 17 to 18 weeks, most pregnant women can start to feel fetal movements or kicks. On average, you should be able to count six kicks or movements per two-hour window. If you sense that the baby isn’t moving enough or that something isn’t right, check with your healthcare professional.