Hearing the baby’s heartbeat for the first time is one of the most precious milestones for expecting parents. It is also one of the most important steps for a doctor to confirm pregnancy. When does the fetal heart start functioning, and how soon can you hear it? What does it mean if you can’t hear it in the first scan? Read on to know all about it.
After successful fertilization, the embryo starts developing rapidly. The cells will begin merging to form a fetus, and the fetal heart will start functioning as early as 4 weeks after conception. A woman can detect her pregnancy as early as 2 weeks after conception – which is 4 weeks after her last menstrual period. So, the baby's heartbeat starts as early as 6 weeks after LMP.
The heart is responsible for circulating oxygenated blood and nutrients to all the developing organs. The functioning of the heart is one of the first and most important steps for the baby’s body to start developing. The baby’s heartbeat is one of the first signs a doctor will look for during an early pregnancy scan to confirm pregnancy. Without a heartbeat, the pregnancy is not viable.
By 6 weeks after LMP, which is also known as the 6th week of pregnancy, the baby’s heart is still developing. Though for an expecting parent, it is a “heartbeat”, technically, it is “cardiac activity”.
During an early pregnancy ultrasound, which is usually taken around week 6-8 of pregnancy, you can see the cardiac activity. This can vary from pregnancy to pregnancy, and most doctors wait till the completion of week 6 to take this early pregnancy scan.
You can see the cells fluttering rapidly in this early pregnancy scan. You may or may not hear the heartbeat, depending on the position of the baby. If the baby is tucked away in some corner of the uterus, it can be difficult to hear a steady heartbeat, though you can clearly see the cardiac activity.
In such cases, you can hear the heartbeat in the next ultrasound as the baby will be bigger, and the heartbeat will be stronger and louder for the ultrasound to pick up.
Around week 15, you can hear the fetal heartbeat with a Doppler. Around week 20, you can listen to the heartbeat with a stethoscope.
A fetus’s heart does not beat rhythmically like an adult’s. The expecting mother’s and the developing baby’s hearts will beat very differently. This is because your baby’s heart will beat much faster than yours. While an average adult’s resting heart rate can be between 60 and 100 beats a minute, a fetal heart beats 110 to 160 times a minute. So, it can sound more like a galloping horse rather than the rhythmic heartbeat you are used to.
A baby’s heartbeat at 6 weeks of pregnancy can be around 110 times a minute. It will increase up to 150 to 170 times a minute in week 8 and go up further to 170 in week 10. Around week 20, the heart rate will slow down to 140 beats a minute.
Doppler is a small handheld device that doctors use to hear the baby’s heartbeat during routine prenatal visits. They will apply a gel and press the Doppler against your belly to hear the heartbeat. You can use a Doppler at home, too, but doctors strongly advise against this. The reason is that you may not know how to use it, or if the baby is not in position, it can be difficult to pick a heartbeat, which h can lead to confusion and panic, thus affecting the mother’s mental and physical health.
During labour, the baby’s heart rate can range anywhere between 110 and 160 beats per minute. The heart rate can go higher or lower than this range, for various reasons. This is normal and nothing to worry about.
The baby’s heart starts developing very early in pregnancy and continues to develop even after the delivery. Here is how the baby’s heart develops during the course of pregnancy:
After your LMP, around week 4, the cells in the embryo will come together to form the heart. By week 5, cardiac activity will start, resulting in the heart pulsing. The valves and blood vessels will also start forming during this time.
By week 15, the heartbeat is louder and audible through a Doppler. However, if the baby is not in the proper position, it can be difficult to pick the heartbeat. By week 17, the brain starts controlling and regulating the heart.
By week 20, the heart chambers will develop well enough to be visible on an ultrasound. During the 20th-week scan, the doctor will check the baby’s heart and chambers to ensure there are no congenital heart defects.
If the doctor is unable to hear the heartbeat well or is concerned about the heart's functioning, they will order an echocardiogram anytime between weeks 18 and 24.
As the pregnancy progresses, the baby’s heart will develop fully and the circulatory system will also continue to develop. By week 40, or EDD, the baby’s heart is developed enough to face the outside world.
A baby’s heart starts functioning from the early days of pregnancy. It can be very exciting to hear or see your baby’s heartbeat for the first time. Remember, for some babies, it can be easy to find the heartbeat, and for some, it can be challenging.
● A baby’s heartbeat is usually detected by an ultrasound taken around the 8th week of pregnancy. During this time, the heartbeat may not be audible but the scan can pick up the cardiac activity. The heartbeat can be audible from the 15th week onwards. You can hear it using a Doppler. A stethoscope can pick up the heartbeat after week 17.
● Don’t panic if you can’t heartbeat. It could be too early, or the baby might not be in a good position to catch the heartbeat. If you are trying to hear the heartbeat using a Doppler at home, you may be using it wrong. Seek advice from your doctor who can check for the heartbeat with a Doppler or a stethoscope or take an ultrasound to check on the baby’s activity. If the doctor can’t detect the heartbeat, they can order an echocardiogram for a closer inspection of the baby’s heart.
● Some common factors that can affect fetal heart rate are – gestational age, the mother’s health condition, whether the baby is in a resting or an active phase, the mother’s medications, if in labour – the stage of labour, tests done during labour, etc. Everything that affects the mother can affect the baby and impact the heart rate.
● A baby’s heartbeat can be detected as early as 6 weeks after LMP. You may not hear it by this time, but you can see some cardiac activity or steady pulsing during an ultrasound. You can hear the heartbeat using a Doppler or a stethoscope or during an ultrasound after week 20.
