A home fetal doppler is a hand held device for pregnant women to listen to the fetal heart rate. These devices are similar to the fetal dopplers used by the OB, midwife, or nurse for listening to the baby’s heartbeat at appointments. Fetal dopplers are a type of ultrasound machine, but not the kind that will show a picture of the baby. With a fetal doppler, you can hear the mother’s blood flow, blood flow in the placenta, baby’s movements, and the baby’s heartbeat. However, the FDA’s position is that over-the-counter sale of home fetal dopplers creates an undue risk. So here’s what you need to know as you consider whether or not to buy a home fetal doppler.
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Why does the FDA caution against home fetal dopplers?
Being able to hear the baby’s heartbeat at home between appointments sounds pretty great. So why aren’t they recommended by the FDA or many medical professionals? There are 3 main reasons. First, the potential heat that could be caused by ultrasound use may affect the baby’s development. Second, it’s hard to know what you are listening to if you haven’t been trained in use of the fetal doppler. Sometimes, It can be difficult for trained providers to find the heartbeat, so untrained individuals may have even more difficulty. Finally, hearing a heartbeat can give some pregnant women false reassurance, preventing them from seeking help when there are concerns. Let’s examine each of these three factors more closely.
1. Safety of the home fetal doppler
There are two primary safety concerns with ultrasound: cavitation and heating. Ultrasound can cause cavitation, which means it causes air bubbles to form in tissue. Studies have shown that it is unlikely that cavitation occurs at diagnostic levels of ultrasound. Ultrasound can also produce heat in tissues. In fact, in my field of physical therapy, the modality has been used for years specifically to heat tissues (the evidence for benefit as a therapy treatment is questionable, but that’s a topic for another time). There is concern that the exposure to ultrasound and the heating effect of ultrasound could interfere with the development of the baby in utero. So should you be concerned?
Thermal index of fetal dopplers is very low
The parameters of the ultrasound that is used for tissue heating are different than the parameters for a fetal doppler. Home fetal dopplers have very low output, making them safer! I bought the Sonoline B pocket fetal doppler, and the Thermal index of this model is <1. The thermal index is a measure of the absorption of the sound waves of the ultrasound causing heating of tissue. The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) recommends a TI <1.0 for first trimester screening (11 weeks to 13 weeks, 6 days), limiting exposure time to Doppler imaging for as little as possible, preferably less than 5-10 minutes (for more information, see citation #2 below).
What this means is that the use of an at home fetal doppler is safe, if you set limits for using it
If you plan to use a fetal doppler at home, consider setting limits for yourself for how long and how often you will use the doppler. I set a timer for 10 minutes. At that time, I stop whether I have found a heartbeat or not. I determined ahead of time that I also would not use the doppler more than twice a week, that way I know that I am limiting my exposure time.
2. Difficulty identifying the fetal heartbeat
Finding the heartbeat
Ever go to the OB or midwife and they had trouble finding the fetal heartbeat on the doppler? It happened to me at a 12 week appointment, due to the position of my uterus, and they needed to use ultrasound imaging to find the heartbeat. If trained professionals who do this regularly can sometimes struggle, so much more the rest of us who have never used a fetal doppler before.
If you are considering using a home fetal doppler, it’s important to consider how you will react if you can’t find a heartbeat. Will it cause you a lot of stress? It’s important to temper your expectations if you plan to use a home fetal doppler. Understand that it is not always easy to find a heartbeat, especially early on in the pregnancy. Factors like the mother’s weight and position of the uterus can make it more difficult. Hearing a heartbeat with a fetal doppler is a great bonding experience, but you don’t want to cause yourself to spiral into grief and fear if you can’t find a heartbeat.
Which sound is the heartbeat?
There are many sounds that can be picked up with a home fetal doppler. You can hear your own blood flow. The noise of the baby’s movement and the placenta can also be heard. It’s important to learn about the different sounds before trying to use a fetal doppler. There are videos you can watch and listen to that can help teach you to identify the fetal heartbeat.
3. Home Fetal Dopplers are not a diagnostic tool
Finding a heartbeat with a fetal doppler is a great feeling, but it can’t tell you everything that is going on with the baby. Since home fetal dopplers have become more popular, healthcare providers have been treating more pregnant women who ignored warning signs. Some women noticed less movement, or some bleeding, but they didn’t contact their provider right away. Instead, they found the heartbeat on their fetal doppler and assumed everything was fine. In many of these cases, everything was not fine, and outcomes could have possibly been better if they had called the doctor right away.
If you use a fetal doppler, it’s important to understand that you must still seek medical advice if you have a concern. A fetal doppler can help relieve stress if you’ve had a history of loss. I know with my losses, I often have worried during this pregnancy that something is wrong even though all signs indicated that everything was going well. In this case, where there are no concerning symptoms, hearing a heartbeat for reassurance isn’t a bad thing. But if you experience any concerning symptoms, it’s time to put the doppler away and call the doctor.
Why use a home fetal doppler?
Special moment to share with family and siblings
My son is young, and he doesn’t fully understand the whole idea of a new baby on the way. Listening to the heartbeat together was a more clear way for him to understand. It can also be a nice way to share with family who aren’t at appointments, like grandparents.
Reassurance
As I mentioned above, a fetal doppler can provide some reassurance from anxiety during pregnancy after loss. The time before the baby’s movements can be felt are some difficult weeks for those who have experienced loss. Using a fetal doppler at times can help reduce anxiety. Just be sure to use with caution: call the doctor if you have a concerning symptom! And be prepared for the possibility that you may not be able to find a heartbeat due to the baby’s size and position.
Make a keepsake
One of the things I like to do is record the heartbeat on my phone to listen to over and over. Since I don’t want to use the fetal doppler too frequently, listening to the recording of the heartbeat helps get me through. Once you have a recording, there are many options for heartbeat keepsakes. You can get a stuffed animal with the baby’s heartbeat. Soundwave keepsakes like glass art, wall decor signs, key chains or even jewelry are other special ways to preserve the memory.
How to buy and use a home fetal doppler
If you’ve read this far and are still convinced a home fetal doppler is for you, here are the basics for getting started.
Choosing a home fetal doppler
Home fetal dopplers are very affordable, but not all are made the same. For me, I felt it was important to purchase a doppler that was cleared by the FDA. Because of this, I chose the Sonoline B pocket fetal doppler. I’ve never tried any other dopplers, so I can’t tell you which is best. I would just suggest that you do your homework and buy a brand that is approved by the FDA or a similar level of regulatory agency.
In addition to the doppler, you will also need gel. The gel helps the sound waves from the doppler to go from the transducer on the doppler to your skin. I would recommend that you buy ultrasound gel. It’s really not that expensive, and it is designed for the best transmission of the sound waves.
I had read that you can also use clear aloe vera gel, and so I tried it out. It did work, and I was able to hear the fetal heartbeat and other sounds clearly. I would be concerned about the effect the aloe vera gel may have on the transducer head of the doppler, as I don’t know anything about it. The kind of clear aloe vera gel I would normally buy is only slightly cheaper per ounce anyway. If you really want to try it, aloe vera gel will work, but I prefer to just spend $5 on a bottle of ultrasound gel.
How to use a home fetal doppler
Get set up
Get a small towel, your fetal doppler, and the ultrasound gel within reach. Recline or lay down somewhere comfortable. I would also keep your phone and a pillow handy. The phone can help you keep track of time. I prefer to limit myself to 5-10 minutes, 2x per week or less to minimize exposure. With your phone, you can also record the heartbeat if and when you find it. A pillow can be used to reposition if you’re having trouble finding a heartbeat, and it’s easier if everything is close by once you have that gel on your belly.
Tuck the towel into your pants and/or underwear. This keeps your clothing clean and dry, and lets you easily wipe the ultrasound gel when you’re done. Generously apply ultrasound gel, either to the transducer head of the fetal doppler or directly to your abdomen. In the first trimester, the uterus and baby are mostly within the pelvis, so gel should be applied just above the pelvis. During the second trimester, the uterus and baby grow a bit higher each week, reaching the belly button somewhere around week 20. So if you are less than 20 weeks, keep the gel below your belly button.
Using the home fetal doppler
I prefer to get the transducer head of the doppler in contact with the ultrasound gel and the skin before turning it on. When the transducer head is not in contact with the gel and skin, it can make a loud noise and I prefer to avoid that.
Turn up the volume, so that you won’t miss anything. Slowly move the transducer head, with small changes in position and angle. Especially if you are in the first trimester or early second trimester, start low at the level of the top of the pelvis. Make sure that you can identify sounds correctly, so that you don’t confuse the baby’s heartbeat with blood flow through the placenta or your own heartbeat. These do sound different, so just listen to some recordings beforehand. If you’re not sure, you can always record a bit on your phone and double check later.
If you are having trouble finding the heartbeat, there are a few things you can try. First, try again when you have a full bladder, or when you have an empty bladder. Try a different position. If you were sitting, try reclining or laying down. If you carry some extra weight in your stomach like me, it can be helpful to put a pillow under your hips. You can also use one hand to pull a bit of the extra stomach tissue up and out of the way. If you still can’t find a heartbeat, consider putting it away for a few weeks. As the baby grows, it will become easier to find.
My experience
I bought a home fetal doppler in the first trimester, and made myself wait until 10 weeks. Unfortunately, I couldn’t find heartbeat during those 2 attempts in week 10. During my 12 week appointment, my midwife had difficulty finding the heartbeat and ultimately needed ultrasound. The ultrasound tech said I had a retroverted uterus, which explains some of the difficulty. A few days after my appointment, I tried again. I was still in week 12, but I thought maybe I would have some luck now that I knew the position of the baby after my ultrasound. I still couldn’t find it, and I knew that the baby was alive and well in there.
Due to my history of loss, I also knew my limits. If I continued to have repeated failures to find a heartbeat, I was going to become anxious and defeatist. At 15 weeks, I decided to try again. This time, I was able to find the fetal heartbeat.
Am I glad I bought the home fetal doppler?
Even with my failures to find the heartbeat in the first trimester, I was still happy I bought the fetal doppler. They are fairly cheap, and it was reassuring to hear a heartbeat in weeks 15-17 as I couldn’t feel baby moving yet.
I’ve been able to use it without increasing my anxiety. I’ve set limits for myself, stuck to them, and set accurate expectations. I reminded myself at each use that not finding a heartbeat early on was not an indicator that anything was wrong. And when I needed a break mentally, I put it away for a while. I have also had some spotting during this pregnancy, but due to my history of loss, there’s no way I was ignoring a warning signal. I called my birth center right away, and so should each of you if you notice a concern.
The home fetal doppler has also been a precious opportunity to help my young son understand about the new baby. He has been enjoying it and asks nearly every day to listen. I have to tell him that we need to limit how often we use the doppler, and instead I’ll play him the recording of the heartbeat. In my area, I would have paid $75 or more for one 15 minute private ultrasound. To me, being able to spend $55 on a doppler and gel instead, which I can use multiple times for reassurance and bonding, is more than worth it.
Citations
- https://radiopaedia.org/articles/thermal-index?lang=us
- https://obgyn.onlinelibrary.wiley.com/doi/10.1002/uog.9026
- https://www.bmj.com/bmj/section-pdf/186393?path=/bmj/339/7730/Feature.full.pdf
- https://fda.report/media/137286/COVID-19-Fetal-Monitoring-Guidance.pdf
- Moyano DB, Paraiso DA, González-Lezcano RA. Possible Effects on Health of Ultrasound Exposure, Risk Factors in the Work Environment and Occupational Safety Review. Healthcare (Basel). 2022 Feb 24;10(3):423. doi: 10.3390/healthcare10030423. PMID: 35326901; PMCID: PMC8954895.