When does a foetus have a heartbeat?

A foetus usually develops a heartbeat around 5 to 6 weeks of pregnancy, which can sometimes be detected through a transvaginal ultrasound.

Is no heartbeat at 4 weeks normal?

Yes, it’s normal not to detect a heartbeat at 4 weeks. At this stage, the heart is just beginning to form, and ultrasounds usually cannot pick up heart activity yet.

How Early Can You Hear Your Baby’s Heartbeat?

Hearing your baby’s heartbeat for the first time is an unforgettable moment that makes your pregnancy feel so real. It’s like a little signal from your baby letting you know they’re growing strong inside you.

You may find yourself wondering when this magical sound can be heard and what it will feel like, or even how late a heartbeat can start in pregnancy. At the same time, you may hear stories from friends or read online about hearing heartbeats at different stages of pregnancy, which can make things confusing. Remember, every pregnancy is unique, so the timing can vary. The key is patience and trusting your healthcare professional to guide you.

When Does the Heart Start Beating in Pregnancy?

Your baby’s heart begins to form and function very early in pregnancy, even before you might realise you’re pregnant. Take a quick look at the timeline:

Week 4 to 5 after conception: A cluster of cells in the embryo starts to form what will become the heart. By week 5, these cells begin to pulse and mark the start of cardiac activity in the foetus. This isn’t yet a fully formed heart but a tube-like structure that’s the foundation of your baby’s heart.
Week 6: The heart tube starts to twist and bend, laying the groundwork for the heart’s chambers and valves. This is when you might first see signs of cardiac activity on an ultrasound. It is often described as a flickering of cells.
Weeks 8 to 10: The heart develops its basic structure, including the four chambers (two atria and two ventricles), valves, and major blood vessels like the aorta and pulmonary artery. By week 10, it’s functioning more like a proper heart.

This early pulsing is called “cardiac activity” in a foetus rather than a heartbeat because the heart isn’t fully formed yet. By the time you’re 6 weeks pregnant (calculated from your last menstrual period), this activity can often be detected, confirming that your pregnancy is progressing.

When Can You Hear Your Baby’s Heartbeat?

Hearing your baby’s heartbeat depends on the tools used and the stage of your pregnancy:

6 to 8 weeks (early ultrasound): A vaginal ultrasound can often pick up cardiac activity in the foetus as early as 5 and a half to 6 weeks after conception. You might see a fluttering on the screen, but hearing the heartbeat depends on the baby’s position. It might be harder to detect if the baby is tucked away in a corner of the uterus. Some doctors wait until 8 weeks for a clearer view.
12 to 15 weeks (Doppler): By around 12 to 15 weeks, your doctor can use a handheld Doppler device to hear the heartbeat during a prenatal visit. This device amplifies the sound of the heart’s activity, making that “thump-thump” audible. Factors like the position of your uterus, your body shape, or a full bladder can affect how easily the heartbeat is detected.
20 weeks (stethoscope or ultrasound): By the 20-week ultrasound (also called the level 2 ultrasound), the heartbeat is usually loud and clear. A stethoscope can also pick it up at this stage, as the baby’s heart is stronger and more developed. If you’ve been thinking about how late a heartbeat can start in pregnancy, by this point, it is typically easy to detect.

What Does a Foetal Heartbeat Sound Like?

The sound of your baby’s heartbeat is often described as the galloping of horses: fast and rhythmic. Unlike an adult’s heart, which beats 60 to 100 times per minute at rest, a foetal heartbeat is much quicker:

6 to 7 weeks: The heart pulses at 90 to 110 beats per minute (bpm).
8 to 10 weeks: The rate peaks at 150 to 170 bpm, about twice as fast as yours.
20 weeks onward: The heart rate slows to around 110 to 160 bpm, which is considered normal for the second and third trimesters.

You might also hear a whooshing sound during an ultrasound or Doppler, but this is usually blood flow through the placenta or your own blood vessels, not the heartbeat.

Why You Might Not Hear the Heartbeat

If you don’t hear the heartbeat at your first ultrasound, don’t panic. It doesn’t always mean something’s wrong. These are some common reasons for it:

Too early in pregnancy: If you’re earlier than expected, the cardiac activity in the foetus might not yet be detectable. Your doctor may adjust your due date and suggest a follow-up scan in 1 to 2 weeks.
Position of the uterus: A retroverted (tipped) uterus can make it harder to pick up the heartbeat, as the baby may be positioned further from the ultrasound wand.
Body shape: A larger abdomen or extra tissue can interfere with the ultrasound’s ability to detect the heartbeat.
Baby’s position: The heartbeat might be harder to find if the baby is tucked away or facing a certain direction.
Possible complications: In rare cases, no heartbeat could signal a miscarriage (if the embryo’s crown-rump length is over 5 mm with no heartbeat) or an ectopic pregnancy (where the embryo is outside the uterus). Your doctor may order a blood test or another ultrasound to confirm.

How is the Heartbeat Detected?

Your doctor uses specific tools to detect and monitor your baby’s heartbeat:

Vaginal ultrasound: Used early in pregnancy, this gives a clear view of the embryo and can detect cardiac activity. It’s more accurate than an abdominal ultrasound at this stage.
Abdominal ultrasound: This is common for the first ultrasound to check for a viable pregnancy, heartbeat, and gestational age, especially after 7 and a half weeks.
Handheld Doppler: This device uses ultrasound gel and is moved over your belly to amplify the heartbeat. It’s painless and used at routine prenatal visits around 12 to 15 weeks.
Stethoscope: By the second trimester, a stethoscope can pick up the heartbeat as the heart grows stronger.

Tips for a Healthy Foetal Heart

Try these simple steps to support your baby’s heart development:

Take prenatal vitamins to provide essential nutrients.
Avoid smoking, vaping, alcohol, and recreational drugs, as these can harm foetal development.
Attend all prenatal appointments to monitor the heartbeat and overall growth.

Hearing your baby’s heartbeat is an exciting milestone that reassures you that your little one is growing. You might be thinking about how late a heartbeat can start in pregnancy, but the exact timing can differ for everyone. So don’t worry if it happens a bit earlier or later than you expected.

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FAQs on How Soon Can I Hear My Baby’s Heartbeat?

When does a foetus have a heartbeat?
A foetus usually develops a heartbeat around 5 to 6 weeks of pregnancy, which can sometimes be detected through a transvaginal ultrasound.
Is no heartbeat at 4 weeks normal?
Yes, it’s normal not to detect a heartbeat at 4 weeks. At this stage, the heart is just beginning to form, and ultrasounds usually cannot pick up heart activity yet.