Fetal Heart Rate and Heart Sound: What is the difference?

New Born baby

When receiving an ultrasonic examination in obstetrics and gynecology to see the appearance of the baby in the tummy, the doctor may talk about the baby’s heartbeat. Many moms feel uneasy when told that the baby’s heart rate cannot be checked yet.

Stethoscopes that can hear a baby’s heart sound are available in the market. This may cause confusion about the difference between heartbeat and heart sound. You may wonder whether heartbeats and heart sounds are different, and if you can identify the heartbeat from the heart sound with a stethoscope.

Therefore, we have summarized the difference between heartbeat and heart sound of a tummy baby, and when each can be confirmed.

Difference between heartbeat and heart sound

Both heartbeats and heart sounds are related to the movement of the heart of a baby who is in the tummy, but there are differences.

Heart Rate

Baby’s heart motion that can be checked on the monitor during ultrasound examination

Heart sound

By hitting the equipment, you can hear from outside your stomach the sound of the baby’s in the tummy

When you see the baby on the monitor by ultrasonic examination, you can view the heart moving with a certain rhythm. The beat is “heartbeat”, the sound of the baby’s heart that you can actually hear is the “heart sound”.

It may be easier to understand if you think of the heartbeat as something that you can check with your eyes, while the heart sound can be confirmed by your ear.

When heart beat and heart sound can be confirmed

Heart rate: around the sixth week. As early as 5th week of pregnancy, and will be able to confirm by late 8th week
Heart sound: around the past 12 weeks

A tummy baby changes to a more human figure by repeating the division of the cell called embryo. Among the organs, the heart which carries oxygen and nutrition to the whole body is made at an early stage. So when it comes to about 6 weeks and it is almost finished, it will be possible to check the baby’s heart rate with ultrasound.

If the heart rate can be confirmed with the embryo, there is a definite diagnosis of normal pregnancy, and a maternal and child handbook can be issued.

Difference of ovulation day due to menstrual irregularity

The number of gestational weeks is calculated based on the 28th day cycle and starting from the beginning of the last menstruation day. For that reason, people with cycles of 28 days and people of 30 days have errors of about 2 days.

If the ovulation day is delayed, the error may cause the time to cause confusion; so that it may happen that one might think it’s the sixth week when it’s actually the fifth. In that case, the fetus is still in the 5th week, so it may not be possible to check the heart rate.

Position problem

Even if your baby’s heart is moving, the intestines may get in the way and you may not be able to check with ultrasound.

Possibility of miscarriage

Even if the womb is made, if the condition where the embryo or the heart beat cannot be confirmed continues, there is a possibility of miscarriage in which the growth of the baby has stopped. Since these are mostly problems on the baby’s side such as chromosome abnormality, please do not blame yourself.

If you are told that you cannot confirm the heart rate by ultrasonic examination in the early pregnancy, you might get worried, but you may be able to check again if you consult the doctor next week etc. Trust your doctor, or if you are too anxious, get a second opinion from another doctor and wait for the next examination.

Even if you can’t hear the heartbeat of your baby, don’t worry too much and too soon. You need to talk with your doctor first and check it again.

I want to hear the heart sound of my baby!

Many mommies may want to hear the heart sound even every day to make sure that the baby is growing up well or not – including dad who cannot attend medical examination because of work, and grandpa and grandma who are looking forward to the birth of grandchild. People in the family naturally feel the excitement.

Since a small fetus is enclosed in a thick amniotic membrane filled with amniotic fluid, you may not be able to check the heart sounds even if you apply a stethoscope. It is at around 7 months that you can hear it from the stethoscope.

Therefore, in order to listen to the baby’s heart sound early in pregnancy, we use a device called “ultrasound doppler” ultrasound. You can listen to the baby ‘s beat with the sound of the frequency of the “reflected wave” from the fetus. Although it is sometimes used at a hospital during medical examination, it is also sold for home use.


Pregnancy may be a period of stuffiness and discomfort  for the mother which the growing baby hardly realizes, but when one sees the baby’s heart moving strongly on the monitor, we feel impressed that we are all living so hard.  At the same time, the awareness will encourage mothers to review her lifestyle more seriously and protect her baby.

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