When Does a Fetus Develop a Heartbeat?

baby heartbeat

For a mother, nothing is more soothing than hearing her baby’s first heartbeat. But when does it start beating, and how can you tell?

The baby’s heart continues to develop throughout the pregnancy. However, some sources claim that it can begin beating as early as 4th week of pregnancy. One can also see a visible sign of heart formation during the early weeks of pregnancy, also known as the fetal pole.

Generally, before the 8th week of pregnancy, a doctor refers to a fetus as an embryo. In case you are interested to know about the stages and development of the embryonic heart or want to know what to expect from your appointments. Keep reading!

When can you hear your baby’s heartbeat?

Cells beating in the heart tube can be heard around the fifth to sixth weeks after conception during ultrasound appointments. The flickering of cells within the torso of the embryo indicates the development of the heart tube.

The ultrasound machine translates this heartbeat and is known as cardiac activity. In reality, heart formation occurs at about the 10th-12th week of pregnancy.

If an ultrasound is not scheduled during the first trimester, you can hear the heart tube beating with the help of Doppler. A caregiver may find a cardiac activity with a handheld Doppler around the 10th week.

Note: The identification of the heartbeat in a fetus varies due to several factors like the position of the uterus, bladder, and belly shape.

What are the several ways through which a heartbeat can be detected?

fetus heart beat

Scans are usually performed to check the fetus condition and the heart’s development. You may be asked to start with an early scan in case of bleeding, pains, or if you had a problem with your previous pregnancy.

Transvaginal Ultrasound

This is done during the early stages of pregnancy (before 11 weeks). This type of scan is internal and can help to detect a heartbeat.

The healthcare provider may also recommend a transvaginal scan after 11-12 weeks if abdominal ultrasound technology fails to provide a precise analysis.

Transabdominal Scan

This is done during the second and third trimesters, and a handheld ultrasound scanner is used to find the uterus and fetus. This procedure is entirely painless, and an ultrasound gel detects a heartbeat.

Sound waves are detected by the scanner and processed, amplified by the device, after which you finally hear the heartbeat.


This kind of heart rate monitoring is done during labor and measures the changes in pulse rates.

Electronic fetal monitoring:

this is done using internal or external equipment and measures the heart rate with respect to contractions. A constant ongoing reading can be checked at particular specified times.


This is carried out with the help of a special stethoscope or Doppler and helps to listen to the fetal heart rate.

What can an embryonic or fetal heartbeat sound like?

baby checkup

Mothers claim that a baby’s heartbeat can sound like “galloping horses”. The embryonic heartbeat beats about 110 to 160 beats per minute. The baby’s size changes as the weeks pass, and with this, the development of the heart also varies.

Hearing a whoosh-type sound is generally because of the movement or monitor passing by the placenta and not a heartbeat. The common experience of “double beats” does not necessarily indicate the formation of twin embryos since a monitor can detect your heartbeat.

Can human ears hear fetal heartbeats?

The fetal or embryonic heartbeat is very difficult to be detected by the human ear. Although, in a quiet room during the late second or third trimester of pregnancy, a mother can hear her baby’s heartbeat.

Do apps help to hear a baby’s heartbeat?

Several apps claim to tell a baby’s heartbeat at home. These apps and devices can give inaccurate readings that can cause worry or panic. So, talk to your health care provider before opting for DIY devices or apps.

Can you tell the gender of the baby based on heartbeats?

No. The embryo’s heart rate cannot predict the sex of the baby.  Although it is said that if the heartbeat measurement is above 140 bpm, one is likely having a girl and if below that, it is a boy. Knowing about pregnancy truths and postpartum beforehand is best to avoid breaking into myths.

Are heartbeat changes normal throughout the pregnancy?

development of fetus in womb

The fetal heartbeat can differ from 5 to 25 beats per minute during pregnancy. The heart rate may also change as a form of adaptation to the uterus conditions.

Meanwhile, it is common for mothers to see heart palpitations. These can lead to a heart racing, pounding, or a change in heart rate.

Why can you not detect a heartbeat?

Your doctor may be unable to find a heartbeat due to an early scan, a larger abdomen, ectopic pregnancy, or other factors.

An early scan can be miscalculated based on the last period. In case a heartbeat is not detected in the first sitting, your healthcare professional may ask you to schedule another appointment.

When can you use a Doppler to hear your baby’s heartbeat?

At around the 15th-16th weeks of pregnancy, you may be able to detect fetal cardiac activity by listening for the sound of the baby’s heartbeat using an ultrasound device placed on your belly.

Experts, such as the FDA, advise against using at-home Doppler ultrasounds unless you’re under the direct supervision of a medical professional because they could be dangerous.

These devices aren’t as sophisticated as medical ultrasound machines used by physicians, so they may not detect a baby’s heartbeat properly. They’re also difficult to operate without proper training. For example, you might think you’ve heard your baby’s heartbeat when really you’re hearing your own heart beating.

How does the heart and circulatory system of your infant develop?

fetus development heartbeat

Early in pregnancy, the embryonic heart begins to develop, and as your kid adjusts to life outside the womb, his heart continues to change long after delivery.

During the first trimester

By week four, a distinct cluster of cells has formed inside your uterus, which will soon form your unborn child’s heart and blood vessels. By week five, these early embryonic structures start beating spontaneously.

During the first few days after conception, the developing embryo looks similar to a long, thin tube that twirls and branches into two tubes. These precursor vessels later develop into the heart and lungs.

During the second trimester development

The fetal brain has begun to regulate the heartbeat by 17 weeks in preparation for life in the outside world. (Up until this point, cardiac electrical activity had occurred on its own.)

During the second trimester, capillaries form at an exponential rate. These teeny-tiny blood vessels transport oxygenated blood to your baby’s tissues and recycle deoxygenated blood back into the circulatory system.

The heart chambers have developed sufficiently between 17 and 20 weeks to be visible on an ultrasound. Your doctor will examine the structure of your baby’s heart and look for any congenital heart defects during your second-trimester anatomy scan.

If your doctor thinks your fetus has any of these conditions, he or she might suggest a fetal echocardiogram (FETAL ECHO) between 18 and 24 weeks. You’ll need to make sure you schedule one if you have a history of congenital heart disease, or if you have type 1 or 2 diabetes, phenylketonuria, or an autoimmune disorder.

During pregnancy third-trimester development

By 40 weeks, the baby’s circulatory system will be fully developed enough to allow him/her to leave the uterus.

How fetal heart works?

fetus develop a heartbeat

During pregnancy, the fetal circulatory system grows rapidly but functions quite differently from when your baby is an adult.

Because unborn children don’t breathe until they’re born, their developing circulatory systems rely on the umbilical cords for a steady supply of nutrients and oxygen-rich blood.

Your umbilical cord transports oxygenated blood and nutrients from your placenta to your fetus, then carries away wastes and carbon dioxide.

Most of the physical changes that occur during the development of the human fetus help direct blood away from the developing lungs, which simply aren’t necessary at birth.

Fetal hearts have:

  • There are three shunts. They divert blood away from the lungs, the liver, and the kidneys.
  • A ductus arteriosus. This fetal vessel connects the pulmonary arteries (which will eventually carry oxygenated air from the heart to the baby’s lung) and the aortic arch (which will carry deoxygenated red cells from the heart to the rest of the baby’s body). It diverts some of the flow away from the baby’s brain and spinal cord.
  • A foramen ovale. This hole between the two upper chambers of the left side of the human body shunts blood away from them.

After birth, all these fetal characteristics gradually disappear or become less apparent. As soon as the umbilical cord has been severed, the fetus begins breathing normally, the fetal circulation shuts down, and the shunts open up again. Everything is back to normal.

Your unborn child’s heart is swiftly developing and changing from the moment a pregnancy test results in a positive result. Take your prenatal vitamin during your pregnancy, stop smoking or vaping (if you presently smoke), stay away from alcohol, and avoid recreational drugs to assist ensure that his ticker has the best possible start. Along the journey, take pleasure in these achievements. You’ll soon be able to hold your newborn in your arms and hear his tiny heartbeat next to your own.


Fetus development is a complex and gradual process. There are many ways to monitor the baby, which include paying attention to movements and attending ultrasounds and prenatal appointments. Reading pregnancy guides can help you go through the process with ease.

If you are using a home Doppler, talk to your doctor about it. Do not reach any conclusion on your own. It is highly advised to let your caregiver know of the situation if you feel any change or unusual pain at any point in time.