Table of ContentsView AllTable of ContentsWhen It Is UsedHow It WorksIs It Safe?Frequently Asked Questions
Table of ContentsView All
View All
Table of Contents
When It Is Used
How It Works
Is It Safe?
Frequently Asked Questions
A fetal doppler is a handheld ultrasound tool that uses sound waves to listen to a fetal heartbeat. Healthcare providers and midwives use these medical devices beginning late in the first trimester of pregnancy as part of routine prenatal care.
More recently, fetal dopplers have been sold over the counter (OTC) for at-home use. Use outside of medical settings is discouraged, however, because the long-term health effects are unknown and its use may lead to inaccurate conclusions about the fetus.
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The fetal heart begins beating around five to six weeks' gestation. Around that time, a fetal heartbeat may be detected with a transvaginal ultrasound. The heart sounds need to get quite a bit stronger, however, before they can be detected with a fetal doppler.
During Pregnancy
Some reasons fetal heart tones may not be detected early on in pregnancy include:
If your healthcare provider ormidwifehas difficulty obtaining fetal heart tones, especially if you are closeto 12 weeks, they may recommend an ultrasound, which is able to find heart activity much earlier—often as early as five or six weeks.
During Labor
Intermittent monitoring with a doppler is usually done every 15–30 minutes during the first stage of labor and every 5–15 minutes in the second stage.People experiencing pregnancy complications are monitored more frequently.
How Is an Ultrasound Used During Pregnancy?
A fetal doppler is a type of ultrasound that uses sound waves to detect fetal and placental sounds. It gets its name from how it works, using the Doppler effect. That is, it detects how waves of frequency—in this case sound waves—change as the observer moves toward or away from the source of the sound. Unlike an ultrasound scan, a fetal doppler only produces sound, not an image.
Sounds are audible through the speaker on the main unit. Some dopplers display the number of heartbeats on the main unit, while others require the practitioner to count them manually.
Fetal heart tones typically fall between 110 and 160 beats per minute. Often heart tones change in response to activity or contractions, which is why it’s important to monitor fetal heart tones during labor.
An abnormal heart rate could indicate that the fetus is not getting enough oxygen or is having other problems.When heart tones fall outside of the expected range, a healthcare provider may recommend further testing or intervention.
Types
Some dopplers are made to be waterproof so that a user can submerge the probe in the water. These dopplers are particularly useful when a person is laboring in water.
Dopplers come in a variety of strengths, measured in megahertz (MHz). MHz is defined as one million cycles per second. Fetal dopplers used in healthcare provider’s offices and sold for OTC use are usually 2 MHz or 3 MHz. For comparison, a probe used for a transvaginal ultrasound can be as high as 5 MHz.
Is Still’s Murmur (Musical Heart) Dangerous?
Other Devices
While there is currently no evidence of harm from doppler use, the Food and Drug Administration (FDA) advises against using an OTC fetal doppler recreationally because the effects of repetitive use are unknown.
Ultrasound can heat and produce small bubbles in tissues. When exposure is increased, such as with repetitive at-home use, the potential for harm to the fetus and the parent increases.Also, when an untrained person uses a doppler, readings from the device may be misinterpreted, causing unnecessary alarm or a false sense of security.
A Word From Verywell
A fetal doppler is a reliable tool for health professionals to listen to a fetus’s heartbeat duringpregnancyand in labor.
Fetal doppler can pick up a fetus’s heartbeat sometime around 10 to 12 weeks of gestation. The heart begins beating at five or six weeks gestation, but you won’t be able to hear it on a fetal doppler that early. In early pregnancy, a transvaginal ultrasound is used to detect a heartbeat.
The FDA advises against home use of doppler ultrasound heartbeat monitors. According to the FDA, these devices should only be used under the supervision of a healthcare professional. This is because at-home use is not controlled, and the number of sessions or the amount of time scanning increases the potential for harm to the fetus.In addition, using a fetal doppler without training can cause additional anxiety for the mother. At times, it may be difficult to find a heartbeat, which can cause unnecessary worry and stress.
The FDA advises against home use of doppler ultrasound heartbeat monitors. According to the FDA, these devices should only be used under the supervision of a healthcare professional. This is because at-home use is not controlled, and the number of sessions or the amount of time scanning increases the potential for harm to the fetus.
In addition, using a fetal doppler without training can cause additional anxiety for the mother. At times, it may be difficult to find a heartbeat, which can cause unnecessary worry and stress.
8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.U.S. Food and Drug Administration.Avoid fetal “keepsake” images, heartbeat monitors.Cleveland Clinic.Prenatal care & your first pregnancy appointment.Edwards K, Itzhak P.Estimated date of delivery. National Center for Biotechnology Information.American College of Obstetrics and Gynecologists.Obesity and pregnancy.Blix E, Maude R, Hals E, et al.Intermittent auscultation fetal monitoring during labour: A systematic scoping review to identify methods, effects, and accuracy.PLoS One. 2019;14(7):e0219573. doi:10.1371/journal.pone.0219573Michigan Medicine University of Michigan.Fetal monitoring during labor.John Hopkins Medicine.Fetal heart monitoring.U.S. Food and Drug Administration.Ultrasound imaging.
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.U.S. Food and Drug Administration.Avoid fetal “keepsake” images, heartbeat monitors.Cleveland Clinic.Prenatal care & your first pregnancy appointment.Edwards K, Itzhak P.Estimated date of delivery. National Center for Biotechnology Information.American College of Obstetrics and Gynecologists.Obesity and pregnancy.Blix E, Maude R, Hals E, et al.Intermittent auscultation fetal monitoring during labour: A systematic scoping review to identify methods, effects, and accuracy.PLoS One. 2019;14(7):e0219573. doi:10.1371/journal.pone.0219573Michigan Medicine University of Michigan.Fetal monitoring during labor.John Hopkins Medicine.Fetal heart monitoring.U.S. Food and Drug Administration.Ultrasound imaging.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
U.S. Food and Drug Administration.Avoid fetal “keepsake” images, heartbeat monitors.Cleveland Clinic.Prenatal care & your first pregnancy appointment.Edwards K, Itzhak P.Estimated date of delivery. National Center for Biotechnology Information.American College of Obstetrics and Gynecologists.Obesity and pregnancy.Blix E, Maude R, Hals E, et al.Intermittent auscultation fetal monitoring during labour: A systematic scoping review to identify methods, effects, and accuracy.PLoS One. 2019;14(7):e0219573. doi:10.1371/journal.pone.0219573Michigan Medicine University of Michigan.Fetal monitoring during labor.John Hopkins Medicine.Fetal heart monitoring.U.S. Food and Drug Administration.Ultrasound imaging.
U.S. Food and Drug Administration.Avoid fetal “keepsake” images, heartbeat monitors.
Cleveland Clinic.Prenatal care & your first pregnancy appointment.
Edwards K, Itzhak P.Estimated date of delivery. National Center for Biotechnology Information.
American College of Obstetrics and Gynecologists.Obesity and pregnancy.
Blix E, Maude R, Hals E, et al.Intermittent auscultation fetal monitoring during labour: A systematic scoping review to identify methods, effects, and accuracy.PLoS One. 2019;14(7):e0219573. doi:10.1371/journal.pone.0219573
Michigan Medicine University of Michigan.Fetal monitoring during labor.
John Hopkins Medicine.Fetal heart monitoring.
U.S. Food and Drug Administration.Ultrasound imaging.
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