One of the most exciting – and nerve-wracking – milestones of pregnancy is the moment you get to hear your baby's heartbeat. You may be able to see the flutter of cells in the heart tube for the first time when you're about 6 weeks pregnant if you have an early ultrasound exam.
If you don't have a first-trimester ultrasound, you'll probably first hear your baby's heart with a handheld Doppler at a regular prenatal visit.
Advertisement | page continues below
Your caregiver may be able to find cardiac activity with a handheld Doppler as early as 12 weeks, but the timing depends on a number of factors, including the position of your uterus, your belly shape, and how full (or empty) your bladder is.
When does a baby have a heartbeat?
At 5 to 6 weeks of pregnancy, there's a flickering of cells within the embryo, referred to as the "fetal pole" at this stage. This flickering is the developing heart tube.
At this point, the heart isn't the four-chambered organ we're familiar with. It's a tube-shaped structure that has a lot of developing to do. The heart tube bends and twists to eventually form the heart, including its chambers.
Because the heart isn't yet developed, the American College of Obstetrics and GynecologistsOpens a new window (ACOG) defines this movement as "cardiac activity" rather than a heartbeat.
"What pregnant people may hear is the ultrasound machine translating electronic impulses that signify fetal cardiac activity into the sound that we recognize as a heartbeat," ACOG states. The group recommends waiting until the heart is fully formed before using the term "heartbeat."
A baby's heart is one of the first structures to form, because it's needed to deliver oxygenated blood and nutrients to other developing organs.
Some of the important steps in heart development are:
Advertisement | page continues below
- Week 6: The heart tube twists and bends into an S shape, and the bottom of the tube moves up to form the two upper heart chambers (atria).
- Week 7: The middle of the tube forms the two lower chambers (ventricles).
- Week 8: Walls form to divide the chambers, each with an entrance and exit for blood flow. Valves form between the ventricles and the aorta (large blood vessel) and pulmonary artery.
- Weeks 9 and 10: The aorta and pulmonary vein are developed, completing the heart's basic structure.
- Birth: The opening between the two atria closes. Your baby is now getting oxygen from their lungs instead of from the placenta.
What does a fetal heartbeat sound like?
Many women say that the beating of their baby's tiny heart sounds like galloping horses. The embryonic and fetal heartbeat is fast, about 110 to 160 beats per minute.
If you hear a whooshing noise, that's not the heartbeat – it's probably because of movement or the monitor traveling past your placenta. Also, if you hear two heartbeats, don't assume you're having twins. You're likely hearing your own heartbeat in the background.
If your baby's heart rate is healthy, it's a sign that development is progressing normally. The chances of a miscarriage once you see or hear a heartbeat are less than 10% at 6 weeks and less than 1% at 9 weeks.
What's a normal fetal heart rate?
Your baby's heart rate will change throughout the course of your pregnancy.
Advertisement | page continues below
It's at its highest early on in the pregnancy, around weeks 8 to 10, when the walls and valves of the heart are forming. The normal range for that period is 150 to 170 bpm (beats per minute).
After week 10, the normal rate will drop to a range between 110 and 160 bpm.
What if my provider can't detect a heartbeat?
If your healthcare provider doesn't find your baby's heartbeat on your first-trimester ultrasound right away, it could be because:
- It's too early in your pregnancy and your due date may be off. (This can happen, especially if your menstrual cycle was irregular.) Your provider will schedule another visit in a week or two.
- You have a retroverted uterus. Because of the position of your uterus, your baby can be just a little farther away and harder to detect.
- You're overweight. Extra tissue between the ultrasound wand and the baby may make it harder to detect the heartbeat.
- You've had a miscarriage. If there's no heartbeat when expected (and ultrasound measurements confirm the age) or if cardiac activity was detected and now isn't, this may be a sign of miscarriage.
- You have an ectopic pregnancy. In this case, an ultrasound wouldn't pick up heart motion in the uterus because the embryo isn't there. Although ectopic pregnancies are never viable, they can sometimes develop enough to have heart motion. An ectopic pregnancy is a surgical emergency that can be fatal if not treated quickly.
Just because we don't get the heartbeat right away with the Doppler, it doesn't mean something is wrong.
- Dr. Layan Alrahmani, board-certified ob-gyn and maternal-fetal medicine specialist
How will I usually hear my baby's heartbeat?
Your healthcare provider will check your baby's heart rate with a fetal Doppler (a handheld ultrasound monitor) at each prenatal visit after about 12 weeks.
Advertisement | page continues below
"We use Doppler in the clinic to detect the heartbeat because it's more readily available than ultrasound machines," says Layan Alrahmani, M.D., a board-certified ob-gyn, maternal-fetal medicine specialist, and a member of the BabyCenter Medical Advisory Board. "However, know that ultrasound is the gold standard for detection of fetal anatomy, including the heartbeat. So just because we don't get the heartbeat right away with the Doppler, it doesn't mean something is wrong."
Using a Doppler is completely painless. Your provider will cover the device with ultrasound gel and move it around on your belly until they find a spot where the heartbeat can be detected. The Doppler sends and receives sound waves that safely bounce off your insides, including your baby's heart. The returning sound waves are processed and amplified by the device so you and your provider can hear the heartbeat.
You can rent or buy a Doppler for home use. However, some experts think a home Doppler isn't a good idea.
That's because it can take considerable training and practice to find and correctly identify a baby's heartbeat. You may not be able to hear the heartbeat – not because of an issue with your baby, but due to user error. It's also possible to hear the sound of blood flowing through the placenta or your own blood vessels and mistake it for a heartbeat.
There are better ways to monitor your baby, such as paying attention to your baby's movements and attending all of your prenatal appointments.
Advertisement | page continues below
Key Takeaways
- While your healthcare provider may be able to detect a flutter of cells at week 6 of pregnancy, a fetus's heart isn't truly formed until week 10. Around week 12, you'll be able to see and hear a heartbeat.
- You'll most likely hear your baby's heartbeat through a fetal Doppler, though you may also hear it during a first-trimester ultrasound if you have one.
- There are several reasons your healthcare provider may not be able to find a heartbeat immediately, including due date confusion, a retroverted uterus, and issues with weight.
Was this article helpful?
Yes
No