A fetus typically has a detectable heartbeat as early as 5 to 6 weeks of pregnancy, although it is most commonly detected by ultrasound around 6 to 7 weeks gestation.
At How Many Weeks Does a Fetus Have a Heartbeat? | Understanding Fetal Heart Development
One of the most exciting moments in early pregnancy is hearing or seeing your baby’s heartbeat for the first time. I vividly remember the first time I saw that tiny flicker on the ultrasound screen—it made everything feel real. So, at how many weeks does a fetus have a heartbeat? In most pregnancies, a fetal heartbeat can be detected via transvaginal ultrasound as early as 5 to 6 weeks, but it’s more common to detect it around the 6 to 7-week mark. At this stage, the heart begins to beat regularly, marking a significant milestone in fetal development. In this article, we’ll explore the timeline of fetal heart development, how the heartbeat is detected, and what to expect during early pregnancy.
Early Fetal Heart Development: A Timeline
The development of a baby’s heart begins very early in pregnancy, often before many women realize they are pregnant. The heart starts forming within the first few weeks of conception and goes through several important stages before it becomes a fully functional organ.
1. Week 3: The Heart Begins to Form
In the third week of pregnancy (around 5 weeks from the last menstrual period), the fetal heart starts to form. At this point, it is nothing more than a simple tube made of cells, but it will soon begin to fold and loop to create the more complex structure of a heart.
- Tip: While the heart is beginning to form at this stage, it will not yet be detectable via ultrasound. This is the very beginning of cardiovascular development.
2. Week 5: The Heart Starts to Beat
Around the fifth week of pregnancy (about three weeks after conception), the heart tube begins to contract, which can be considered the first “heartbeat.” However, at this point, the heart is still very simple and does not yet function like a fully developed heart.
3. Week 6: Detectable Heartbeat by Ultrasound
By the 6th week of pregnancy, the fetal heartbeat can typically be detected via a transvaginal ultrasound. At this stage, the heart is beating at about 90 to 110 beats per minute, and you may be able to see the flicker of the heartbeat on the ultrasound screen.
- Tip: Some women may not be able to detect the heartbeat until the 7th or 8th week, depending on the accuracy of dating the pregnancy and the quality of the ultrasound.
4. Week 9: Heartbeat Becomes Stronger
By the 9th or 10th week of pregnancy, the fetal heartbeat becomes stronger and faster, usually ranging from 140 to 170 beats per minute. At this point, the heart has developed four chambers (two atria and two ventricles) and is functioning more like an adult heart.
Table 1: Timeline of Early Fetal Heart Development
| Pregnancy Week | Fetal Heart Development Stage | What to Expect |
| Week 3 (5 weeks LMP) | Heart tube begins to form | No detectable heartbeat yet |
| Week 5 (7 weeks LMP) | Heart tube begins to contract (first heartbeat) | Heartbeat may not be detectable yet |
| Week 6-7 (8-9 weeks LMP) | Heartbeat detectable via transvaginal ultrasound | Heart rate: 90-110 bpm |
| Week 9 (11 weeks LMP) | Heartbeat becomes stronger and faster | Heart rate: 140-170 bpm |
How Is the Fetal Heartbeat Detected?
There are a few different methods used to detect a fetal heartbeat during early pregnancy. The most common method is through ultrasound, but as the pregnancy progresses, other methods become available.
1. Transvaginal Ultrasound (5-7 Weeks)
A transvaginal ultrasound is typically used in the early weeks of pregnancy (around 5 to 7 weeks) to detect the fetal heartbeat. This type of ultrasound involves inserting a small probe into the vagina to get a closer look at the developing embryo and is more sensitive than an abdominal ultrasound at this early stage.
- Tip: Don’t be alarmed if the heartbeat isn’t detected during your first ultrasound. It’s possible that the pregnancy is not as far along as initially thought, or that the baby’s position makes it difficult to detect the heartbeat.
2. Abdominal Ultrasound (After 8 Weeks)
An abdominal ultrasound can detect a fetal heartbeat after 8 weeks of pregnancy. By this time, the fetus is larger, and the heartbeat is stronger, making it easier to pick up via an abdominal probe.
- Tip: Abdominal ultrasounds are less invasive than transvaginal ultrasounds, but they are typically less sensitive in the very early weeks of pregnancy.
3. Doppler Device (12+ Weeks)
Once you reach 12 weeks of pregnancy, your healthcare provider may use a handheld Doppler device to detect the fetal heartbeat during prenatal visits. This device amplifies the sound of the heartbeat, allowing you to hear it externally.
- Tip: Doppler devices are not usually used in early pregnancy, as they are less effective at picking up a heartbeat before 12 weeks.
Table 2: Methods for Detecting Fetal Heartbeat
| Detection Method | When It’s Used | How It Works |
| Transvaginal Ultrasound | 5 to 7 weeks | Probe inserted into the vagina for a closer view |
| Abdominal Ultrasound | 8+ weeks | External probe placed on the abdomen |
| Doppler Device | 12+ weeks | Amplifies the sound of the heartbeat externally |
What to Expect During Early Pregnancy Ultrasounds
The first ultrasound, which usually occurs between 6 and 9 weeks, is an exciting and often emotional experience. However, it’s important to keep in mind that every pregnancy is different, and the timing of detecting the heartbeat can vary.
1. Early Ultrasound (6 to 7 Weeks)
At this stage, your healthcare provider will likely perform a transvaginal ultrasound to check for a fetal heartbeat. During this ultrasound, you may be able to see a small flicker, which is the baby’s heart starting to beat.
- Tip: If no heartbeat is detected, it’s important not to panic. It could simply mean that it’s too early in the pregnancy to pick up the heartbeat. Your doctor may schedule a follow-up ultrasound in a week or two.
2. Follow-Up Ultrasound (8 to 10 Weeks)
If your healthcare provider didn’t detect a heartbeat during the initial ultrasound, a follow-up scan will likely be scheduled around 8 to 10 weeks. By this time, the heartbeat should be easily detectable, and you can expect the baby’s heart rate to be stronger and faster.
- Tip: By the second ultrasound, you may be able to hear the heartbeat if the equipment is sensitive enough, though hearing it is less common at this stage than seeing it.
When to Be Concerned About Not Detecting a Fetal Heartbeat
While most fetal heartbeats are detectable by 6 to 7 weeks, there are times when a heartbeat might not be found during the first ultrasound. There are several possible reasons for this, and in many cases, it doesn’t indicate a problem with the pregnancy.
1. Miscalculation of Pregnancy Dating
One of the most common reasons for not detecting a heartbeat early in pregnancy is a miscalculation of how far along the pregnancy is. If ovulation occurred later than expected, the pregnancy may be younger than initially thought, making the heartbeat difficult to detect.
- Tip: Your healthcare provider may suggest waiting another week or two and then performing another ultrasound to see if the heartbeat is present.
2. Early Pregnancy Loss
In some cases, not detecting a heartbeat can be a sign of early pregnancy loss or miscarriage. If your healthcare provider is concerned, they may conduct additional tests, such as measuring hCG levels or performing a follow-up ultrasound.
- Tip: If you’ve experienced early pregnancy loss before, discuss your concerns with your doctor. They can help monitor your pregnancy closely and offer reassurance.
Table 3: Possible Reasons for Not Detecting a Heartbeat
| Possible Reason | Explanation | What to Do Next |
| Miscalculation of Pregnancy | Pregnancy may be younger than thought | Schedule a follow-up ultrasound in 1-2 weeks |
| Early Pregnancy Loss | Could indicate miscarriage | Your doctor may run additional tests |
| Position of the Fetus | Fetal position may obscure the heartbeat | Recheck after a few days or a week |
FAQs – At How Many Weeks Does a Fetus Have a Heartbeat?
When is a fetal heartbeat first detectable?
A fetal heartbeat is typically detectable by transvaginal ultrasound at around 6 to 7 weeks of pregnancy. In some cases, it may be seen as early as 5 weeks, but this depends on the pregnancy and ultrasound sensitivity.
What should the fetal heart rate be at 6 weeks?
At 6 weeks, the fetal heart rate is usually between 90 to 110 beats per minute (bpm). As the pregnancy progresses, the heart rate increases, reaching 140 to 170 bpm by the 9th week.
Is it normal not to detect a heartbeat at 6 weeks?
Yes, it’s normal not to detect a heartbeat at 6 weeks in some cases, especially if the pregnancy is younger than expected. A follow-up ultrasound will usually be scheduled to confirm the heartbeat.
Can an abdominal ultrasound detect a heartbeat at 6 weeks?
Abdominal ultrasounds are less sensitive than transvaginal ultrasounds and may not detect a heartbeat as early as 6 weeks. A transvaginal ultrasound is the preferred method during the early weeks of pregnancy.
What if no heartbeat is detected at 7 weeks?
If no heartbeat is detected at 7 weeks, your doctor may suggest waiting another week before performing a follow-up ultrasound. It’s possible that the pregnancy is younger than initially estimated, or the fetal position is making it difficult to detect the heartbeat.
How accurate is ultrasound dating in early pregnancy?
Ultrasound dating in early pregnancy is generally accurate within a few days. However, factors such as ovulation timing or irregular cycles can influence the dating, which may affect when the heartbeat is detectable.
When can I hear the fetal heartbeat?
You can typically hear the fetal heartbeat using a Doppler device starting around 12 weeks. Before that, the heartbeat is usually seen on an ultrasound but not heard externally.
What are normal fetal heart rates at different stages?
At 6 to 7 weeks, the fetal heart rate ranges from 90 to 110 bpm. By 9 to 10 weeks, the heart rate increases to 140 to 170 bpm. After that, the rate stabilizes at around 120 to 160 bpm for the remainder of the pregnancy.
Does a strong heartbeat mean a healthy pregnancy?
A strong fetal heartbeat is a good sign of a healthy pregnancy, but it’s just one indicator. Other factors, such as growth and development, are also important for assessing the overall health of the pregnancy.
When should I worry if no heartbeat is detected?
If no heartbeat is detected by 8 weeks, your doctor may investigate further to rule out pregnancy loss. Additional tests like measuring hCG levels or follow-up ultrasounds may be recommended.
Conclusion: At How Many Weeks Does a Fetus Have a Heartbeat?
Celebrating the First Heartbeat Milestone
The detection of your baby’s heartbeat is a special moment that marks a major milestone in your pregnancy. Typically, a fetal heartbeat is detectable around 6 to 7 weeks via transvaginal ultrasound, but don’t worry if it’s not found right away—every pregnancy progresses differently. Whether you hear the heartbeat at 5 weeks or 8 weeks, what matters most is that the heart is beating strong as your baby continues to grow and develop.