Muffled fetal heartbeat. Normal fetal heart rate during pregnancy. Normal heart rate

The fetal heartbeat is the main indicator of the vitality of the unborn child, which reflects its condition and changes immediately as soon as any unfavorable situation arises. That is why doctors monitor the baby’s heart function throughout pregnancy and especially during childbirth.

One of the important indicators of a normally developing pregnancy is the fetal heartbeat. Throughout pregnancy and especially during childbirth, doctors carefully monitor the baby's heart contractions, since the frequency and nature of the heartbeat reflect his general condition.

Heart development is a very complex process. The embryo of the heart in the fetus is laid on and is a hollow tube. Approximately the first pulsating contractions appear, and the heart becomes four-chambered (two atria and two ventricles), i.e. like an adult. Due to the fact that the fetus does not breathe on its own, but receives oxygen from the mother, its heart has its own characteristics - the presence of an oval window (an opening between the right and left atria) and a ductus arteriosus (a vessel connecting the aorta and pulmonary artery). This distinguishes the fetal heart from the adult heart. These structural features of the heart ensure that oxygen reaches all organs and systems of the fetus. After the baby is born, the oval window closes and the ductus arteriosus collapses.

Ultrasound (ultrasound) and echocardiography (echocardiography) are used to assess fetal cardiac activity. Auscultation (listening) of the fetus, CTG (cardiotocography).

Ultrasound of the fetal heart

Early in pregnancy, the fetal heartbeat can be detected using ultrasound (ultrasound). Normally, with a transvaginal ultrasound (the sensor is inserted into the vagina), contractions of the embryo’s heart are detected at 5-6 weeks of pregnancy, and with a transabdominal ultrasound (the sensor is located on the abdomen) - at . In the first trimester of pregnancy (), the heart rate (HR) of the embryo changes depending on the stage of pregnancy. In the heart rate is 110-130 beats per minute, in - 170-190 beats per minute, from and before birth - 140-160 beats per minute. Such changes in heart rate are associated with the development and formation of the function of the autonomic nervous system (that part of the nervous system that is responsible for the functioning of the internal organs of the fetus). Heart rate is an important indicator of embryo viability. Thus, unfavorable prognostic signs are a decrease in heart rate to 85-100 beats per minute and an increase over 200 beats. In this case, it is necessary to carry out treatment aimed at eliminating the cause of the change in heart rate. The absence of heartbeats when the length of the embryo is over 8 mm is a sign of a non-developing pregnancy. In order to confirm a non-developing pregnancy, a repeat ultrasound is performed after 5-7 days, based on the results of which a final diagnosis is made.

Fetal echocardiography

Echocardiography/EchoCG is a special ultrasound test that focuses on the heart. EchoCG is a complex method in which, in addition to two-dimensional (conventional) ultrasound, other operating modes of the ultrasound scanner are used: M-mode (one-dimensional ultrasound, used only for examining the cardiovascular system) and Doppler mode (used to study blood flow in various parts of the heart) . This study allows you to examine the structure and function of the heart and large vessels and is carried out only when indicated.

Indications for fetal echocardiography are:

the pregnant woman's age is over 38 years;
with diabetes mellitus in a pregnant woman;
infectious diseases suffered during pregnancy;
congenital heart defects (CHD) in a pregnant woman;
previous birth of children with congenital heart disease;
intrauterine growth restriction;
detection of changes in the heart during fetal ultrasound (rhythm disturbance, enlargement of the heart, etc.);
identification of other congenital defects or genetic diseases, often combined with heart defects.

The most optimal timing for fetal echocardiography is. At a later stage, visualization of the heart is difficult because the amount of amniotic fluid decreases and the size of the fetus increases.

Auscultation

Another method for assessing the fetal heartbeat is auscultation (listening) to the fetal heart. Auscultation of the fetal heartbeat is the simplest method. To perform it, you only need an obstetric stethoscope - a small tube. An obstetric stethoscope differs from a regular one in that it has a wide funnel, which is applied to the pregnant woman’s bare abdomen; the obstetrician applies her ear to the other end.

During contractions, the obstetrician determines the fetal heartbeat approximately every 15-20 minutes.

Over the years, the shape of the stethoscope has remained virtually unchanged. The classic obstetric stethoscope is made of wood, but nowadays there are also stethoscopes made of plastic and aluminum.

The fetal heartbeat, heard through the abdominal wall, is one of the most important indicators of the vital activity of the fetus, since its character can be used to assess the condition of the fetus.

Fetal heart sounds are heard approximately from the middle of pregnancy, i.e. from, and less often - from. As pregnancy progresses, heart sounds are heard more and more clearly. An obstetrician-gynecologist must listen to the fetal heart during every examination of a pregnant woman and during childbirth. Auscultation of fetal heart sounds is carried out with the pregnant woman lying on the couch.

When auscultating the abdomen of a pregnant woman, in addition to the fetal heartbeat, other sounds are detected: intestinal sounds (irregular gurgling and iridescent), contractions of the aorta and uterine vessels (blowing noises that coincide with the pulse of the woman herself). When auscultating the fetal heartbeat, the obstetrician-gynecologist determines the point of best listening to sounds, heart rate, rhythm and character of heart contractions. Fetal heart sounds are heard as rhythmic double beats with a frequency of approximately 140 beats per minute, i.e. twice as often as in the mother. The point at which heart sounds are best heard depends on the position of the fetus in the uterine cavity. With a cephalic presentation (when the baby is positioned head down), the heartbeat is clearly audible below the navel on the right or left, depending on which direction the fetal back is turned. When the fetus is in a transverse position, the heartbeat can be clearly heard at the level of the navel, on the right or on the left, depending on which direction the baby’s head is facing. And if the child is in the pelvic position, then his heart is better heard above the navel. In case of multiple pregnancy, the heartbeat is clearly detected in different parts of the uterus.

By listening to the fetal heart sounds, the obstetrician determines their rhythmicity: the tones can be rhythmic, that is, they occur at equal intervals of time, and arrhythmic (non-rhythmic) - at unequal intervals. Arrhythmic tones are characteristic of congenital heart defects and intrauterine hypoxia (oxygen deficiency) of the fetus. The nature of the tones is also determined by hearing: clear and dull heart sounds are distinguished. Clear tones are heard clearly and are normal. Deafness of tones indicates intrauterine hypoxia.

The fetal heartbeat may be difficult to hear if:

location of the placenta along the anterior wall of the uterus;
polyhydramnios or oligohydramnios;
excess thickness of the anterior abdominal wall in obesity;
multiple births;
increased motor activity of the fetus.

During labor (contractions), the obstetrician determines the fetal heartbeat approximately every 15-20 minutes. In this case, the doctor evaluates the fetal heartbeat before and after the contraction to find out how the fetus reacts to it. During pushing, the obstetrician listens to the heartbeat after each push, since pushing is a very critical period for the fetus: during pushing, the muscles of the uterus, abdominal wall and pelvic floor of the mother contract, which leads to compression of the vessels of the uterus and a decrease in the supply of oxygen to the fetus.

Cardiotocography (CTG)

It is possible to objectively study the fetal heartbeat using cardiotocography (CTG). Cardiotocography is the simultaneous recording of fetal heartbeats and uterine contractions. Modern cardiac monitors are also equipped with a sensor that allows you to record the motor activity of the fetus.

CTG recording is carried out with the pregnant woman lying on her back, on her side or sitting. Cardiotocography is performed before and during childbirth. The sensor is attached to the pregnant woman's abdomen in the place where the fetal heart sounds can best be heard. The recording is carried out for 1 hour, after which the fetal heart rate and its changes in response to contractions and fetal movements are assessed.

In a number of antenatal clinics equipped with equipment for conducting CTG, this study is performed on all pregnant women, but it is mandatory in the following cases.

From the mother's side:

severe gestosis is a complication of pregnancy in which blood pressure increases, edema appears, protein in the urine, since in this condition blood circulation through the small vessels of the mother’s internal organs is disrupted and, consequently, fetal-placental blood flow and oxygen supply to the fetus are disrupted;
presence of a scar on the uterus;
maternal fever over 38°C;
presence of chronic diseases (diabetes mellitus, arterial hypertension);
induction (causing) labor or labor stimulation when labor is weak;
childbirth during post-term or premature pregnancy.

From the fetus:

polyhydramnios or oligohydramnios;
premature aging of the placenta;
intrauterine growth retardation;
arterial blood flow disorders detected using Doppler ultrasound;
changes in the nature and frequency of heart contractions during auscultation.

After registering CTG, the main (average) fetal heart rate (normally 120-160 beats per minute), heart rate variability (normally, heart rate can change by 5-25 beats per minute), changes in heart rate in response to contractions or fetal movement are assessed , the presence of increased heart rate (so-called accelerations) and slowdowns (decelerations). The presence of increased heart rate in response to uterine contractions and fetal movement is considered a good prognostic sign. A decrease in heart rate can be a consequence of fetal-placental insufficiency and intrauterine fetal hypoxia, and also normally occurs with a breech presentation of the fetus. A decrease in heart rate of less than 70 beats per minute for more than 1 minute is considered a poor prognostic sign.

If necessary (if the condition of the fetus is impaired), CTG is performed repeatedly during pregnancy.

Thus, the study of the fetal heartbeat using various methods is necessary throughout pregnancy and during childbirth, since it allows us to assess the condition of the fetus and promptly carry out the necessary treatment and decide on the method and timing of delivery.

Marina Ershova, obstetrician-gynecologist

Heart rate (HR) is an important indicator that allows doctors to determine the health status of the unborn child.

You can hear the fetal heartbeat already 1 month after conception, but at this stage it is impossible to count the number of beats without special equipment. Heart rate differs at different stages of pregnancy. Accordingly, heart rate norms are determined by week.

Heart rate measurement methods:

Ultrasound (ultrasound examination). The most common way to evaluate the size of the fetus, gestational age, condition of the placenta, etc. Using ultrasound, they listen to heart sounds, examine the structure of the heart, and identify anomalies;
auscultation. Involves listening to the heartbeat using a stethoscope. Determines the approximate heart rate, clarity of tones and presentation of the baby. Even a person without medical education can use the device, but it is effective only from the 3rd trimester. In some cases, auscultation is not possible. For example, if a pregnant woman is overweight, has a small or large amount of amniotic fluid;
Cardiography (CTG). An informative method that allows you to determine the baby’s heartbeat, oxygen starvation and take timely measures. The CTG device is equipped with sensors for uterine contractions and fetal movements. They record the activity of the uterus and examine the waking and sleeping phases of the embryo. The first CTG is performed after 32 weeks. The second is immediately before childbirth. In rare cases, CTG is performed throughout the entire pregnancy according to indications;
echocardiography. It is carried out in the 2-3 trimester if heart defects are suspected in the fetus. EchoCG is an ultrasound examination that studies the structural features of the baby and blood flow.

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Fetal heart rate table by week

The fetal heartbeat during pregnancy is checked for every woman registered. This indicator allows you to:

confirm the fact of pregnancy. After the first delay, the woman is sent for diagnostics. According to ultrasound, from the 3rd week you can hear the heartbeat. If fetal cardiac activity is not observed, an ultrasound scan is performed again after some time. The absence of a heartbeat indicates a frozen pregnancy;
assess the condition of the fetus. The child's heart is sensitive to changes. Stress, maternal illness, the amount of oxygen in the surrounding space, sleep and rest phases are immediately reflected in the heart rate. If the heart beats too fast for a long time, the blood supply to the fetus is disrupted. If it is slow, this indicates a deterioration in the baby’s condition. Correction methods largely depend on the period at which the heartbeat became pathological;
monitoring the condition of the fetus during labor. During the birth process, the baby experiences severe stress and lack of oxygen. Heart rate monitoring allows you to identify difficulties such as umbilical cord compression, placental abruption, and take emergency steps to eliminate the consequences. During labor, the baby's heart rate is checked after each contraction.

There is a belief that the sex of the child can be determined by the fetal heart rate. Allegedly, girls have a heartbeat of 150-170 beats per minute, and boys - 130-150. Therefore, many people think that if, according to an ultrasound, the fetal heart is 146 beats per minute, or, for example, 137, 143, then a boy will be born. And who will be at 167 blows, or 158, 172 - a boy.

This hypothesis is not scientifically confirmed in any way. Gender can only be determined by heart rate with 50% confidence. Heart rate in boys and girls reflects the ability to fight the lack of oxygen. And gender has no influence on this ability.

If you want to find out the sex of your unborn child, contact an ultrasound specialist. Gender can be determined from 15-16 weeks.

The heart rate changes not only according to the baby’s activity phases, but also depending on the stage of pregnancy.

at week 7 the norm is 115 contractions;
on the 8th, the heartbeat can jump to 170 beats per minute;
at 11 weeks, the heart rate usually remains at 150 beats. Minor deviations up or down are acceptable.

Starting from the thirteenth week, doctors constantly check the heart rate using ultrasound, checking the character and rhythm, location of the heart.

From the second trimester, the contraction frequency stabilizes and is 140-160 beats. If the pulse is fast, for example, 170-180, this indicates oxygen starvation. If it is low, less than 120, this indicates fetal hypoxia.

Observation by a doctor

Monitoring the heartbeat is mandatory during childbirth, especially in the presence of any pathologies. The normal heart rate is 140 beats. But sometimes it can reach up to 155.

Baby's heart rate:

Thus, the number of 125 beats is the norm for the initial stages of pregnancy. At later stages, it is considered weak and requires additional examination.

A pulse of 153, 162, 166 beats per minute is natural for periods of 11-40 weeks, for 4-7 weeks it is pathological.

You can find out the sex of the fetus

When determining the heart rate, the doctor evaluates not only the fetal heartbeat, but takes into account additional factors: the presence of a disease in the mother, listening time, whether the baby is sleeping or is in an active state.

When the expectant mother wants to listen to the baby’s heart beat, it is not necessary to visit the clinic. The sound of embryonic development can be heard in the following ways:

stethoscope. A regular obstetric tube is inexpensive and allows you to listen to the baby’s heart. A patient assistant will be required. It is important to learn to distinguish the heart from the sounds of the baby’s movements, pulse, and mother’s peristalsis. Effective from 18-25 weeks;
fetal doppler. Suitable for those who do not have time to master a stethoscope. A portable ultrasound detector works on the CTG principle, but does not provide a graphic image. The kit usually includes headphones. This device is effective from 8-12 weeks, and you can use it until the 38-39th;
putting your ear to your stomach. The method is suitable for late pregnancy, in the 3rd trimester. The place of application depends on the location of the fetus. If your baby is lying head down, place your ear below the navel. With breech presentation – higher. Usually this method is used by men to hear the life emerging in the womb.

Important seven-day periods

The fetal heart is one of the first to form. His work is a special indicator of the development and general condition of the child. Therefore, listening is carried out throughout pregnancy and during childbirth.

Regular monitoring of the heartbeat allows you to detect cardiovascular pathologies in the early stages.

Pronounced myocardial work begins from the 3rd week, but the heart rate can be calculated from the 5th-7th week using an ultrasound scan. At this time, the heart turns into a full-fledged four-chamber organ.

In the early stages, a transvaginal sensor is used to listen to heart rate; already at 6 weeks, an abdominal sensor can be used.

Waiting for a healthy baby

When determining heart rate during pregnancy, the following indicators are important:

contraction frequency. Too fast heartbeat, up to 200 beats/min and above, or slow, less than 100 – these are pathologies that require examination and diagnosis;
character of tones. A healthy heart sounds loud and clear. Blurred and dull tones indicate a disease;
rhythm. Normally, the heart beats again at regular intervals. With acute and chronic hypoxia in the embryo and valve defects, arrhythmia is observed.

Women expecting a child undergo 2 screening ultrasounds, which also determine the heart rate during pregnancy.

The first test is carried out at 12-13 weeks, the second at 21 (some are carried out at 24), the third screening is performed at 32.

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Using ultrasound, the size and condition of the embryo and placenta, the amount of amniotic fluid, the place of its attachment in the body, as well as the normal heart rate of the fetus or whether there are deviations are determined.

Starting from the 19th week, heartbeats are listened to in a simple way - with a stethoscope. Auscultation is performed at every visit to a pregnant women's clinic.

If defects are suspected during an ultrasound, echocardiography is used. It is done at 18-28 weeks. The method allows you to study the condition of the heart and the characteristics of blood flow.

Indications for echocardiography are women over 38 years of age who have children with defects, diabetes mellitus or infectious diseases during pregnancy. Another indication is intrauterine growth retardation.

At 30-32 weeks, a CTG is performed - a recording of the unborn baby’s heart is made. In the early stages, CTG is pointless, since the result will be difficult to decipher. CTG allows you to determine the norm at 32 weeks, namely 140-160 beats per minute.

Attention!

The information published on the website is for informational purposes only and is intended for informational purposes only. Site visitors should not use them as medical advice! The site editors do not recommend self-medication. Determining the diagnosis and choosing a treatment method remains the exclusive prerogative of your attending physician! Remember that only complete diagnosis and therapy under the supervision of a doctor will help you completely get rid of the disease!

Already from the fifth week of pregnancy, the heart of a tiny baby is pulsating, and by the end of the eighth it becomes four-chambered and works fully. At six weeks, you can do a transvaginal ultrasound, which provides the opportunity to hear the fetal heartbeat for the first time. In the future, this process is controlled by the doctor who is managing the pregnancy. He has at his disposal a special tube made of wood - this material transmits sounds well.

The fetal heartbeat is an indicator of the normal development of pregnancy. Too slow or, on the contrary, fast pace may be a sign of violations.

How to hear your baby's heartbeat

You can listen to a child's heart using different methods. More often used is a rather outdated one - auscultation. It involves the use of a Pinara obstetric stethoscope. This tube allows you to listen to the baby's heart during pregnancy, starting from the seventeenth week. Modern methods reduce this period to twelve weeks. In addition, they allow not only the doctor, but also the parents to hear the heartbeat.

If you are using a stethoscope to listen to the fetal heartbeat, you will first need to locate the location where the sound will be best heard and then place the tube on it. Test results depend only on the doctor's experience. The heart rate is assessed over a period of time, so it is not possible to document it.

Another method to monitor the child’s condition is cardiotocography. It allows for continuous monitoring and recording of the heart's performance in graphical form. CTG is performed in the last weeks of pregnancy and immediately during delivery.

Often the fetal heartbeat is assessed during an ultrasound examination. It is performed several times during pregnancy. With its help, you can listen to the baby’s heart as early as the sixth week.

Normal heart rate

When a doctor listens to a baby's heartbeat, the following factors are important:

Heart rate– a very important indicator of a child’s health. A rapid or slow heartbeat is a sign of the development of pathology, which requires prompt examination and treatment.
Rhythm of contractions. Normally, the fetal heart should work rhythmically. Any abnormalities indicate oxygen deficiency and congenital heart defects.
The nature of the heart. Normal heart sounds should be crisp and clear. Deafness is a sign of fetal hypoxia in acute or chronic form.

The heartbeat allows you to determine exactly where the baby is located in the womb. With cephalic presentation, the beats can be heard in the area just below the navel on the left or right side. If the baby lies across, the heart will be heard in the navel area. With breech presentation, the heart beats above the woman's navel.

Muffled beat

The optimal heart rate for an unborn baby is from one hundred seventy to one hundred ninety beats per minute for up to nine weeks. Subsequently, this figure decreases to 140-160. If the fetus has a slow heartbeat - less than one hundred beats per minute - immediate treatment is required. Its main task is to eliminate the factors that caused the heart to slow down.

In some cases, the child’s heartbeat cannot be heard at all. This is possible with:

high or low water levels,
large thickness of the mother's abdominal wall,
multiple pregnancy,
increased fetal activity.

If the length of the fetus is more than eight millimeters, and there is no heartbeat, this indicates a frozen pregnancy. But the final diagnosis can only be made based on the results of a repeat ultrasound, which is performed a week later.

Causes of rapid rhythm in the fetus

Factors such as anemia, cardiovascular diseases, diabetes mellitus, kidney disease, drug and alcohol addiction of the mother cause rapid fetal heartbeat when the number of beats per minute exceeds 200. In addition, such deviations from the norm can cause post-term pregnancy, disturbances of fetal-placental circulation, anomaly of labor.

Closer to the time of birth of a child, the mother’s physical activity, exposure to cold or heat, and exposure to various diseases affect his heart rate.

To identify heart defects, the four-chamber section is carefully studied. In this image, doctors are able to see all parts of the heart and detect about 75 percent of heart defects in the fetus. If there is any suspicion, another examination is performed - echocardiography.

Listening to the fetal heartbeat is a mandatory procedure throughout pregnancy. This allows you to adequately assess the condition of the unborn child, carry out a course of therapy in a timely manner and decide on the timing and methods of delivery.

One of the most touching moments of pregnancy is when the expectant mother hears her baby's heartbeat for the first time. With the help of modern equipment, this can be done as early as 4-5 obstetric weeks. At this point, a small heart has already been formed, which pumps blood throughout the embryo’s body.

Fetal heartbeat- one of the main indicators reflecting the condition and viability of the fetus. If any complications or pathologies occur, the baby’s pulse rate changes. This is why doctors monitor your heart rate (heart rate) throughout pregnancy.

Intrauterine stages of fetal heart development

The heart of the embryo appears under the pharyngeal tube from the ectoderm - the inner layer of the amniotic sac by the end of 3 weeks. Initially, it is a hollow cylinder consisting of the endocardium (inner epithelial layer) and myocardium (middle muscle layer). Due to the presence of a muscle layer, the heart of the embryo begins to beat from the moment it is laid.

At week 4, the mesoderm (the middle layer of the amniotic sac) begins to gather around the organ rudiment, forming the pericardium - a pericardial sac consisting of connective tissue. At this stage, the tube begins to bend, and a thin wall forms at the site of the bend. Before the beginning of the 5th week of pregnancy, the heart of the embryo is two-chambered, consisting of one ventricle and one atrium.

From the beginning of the 5th week of pregnancy, the development of the interatrial septum is observed, which divides the upper chamber into two. At the moment, the structure of the ventricle remains unchanged. Until the end of the 5th week of pregnancy, the heart remains three-chambered.

By the end of the 5th week, another septum appears in the heart primordium, which forms a four-chamber organ. At this point, the circulatory system begins to function. Between the left and right atria, the septum does not completely close, forming an opening - the “oval window”. This anatomical structure plays an important role in the intrauterine circulation of the fetus.

At week 5, the formation of heart valves occurs - structures involved in closing and opening communications between the chambers of the organ with each other and with the vessels. The entire first trimester, especially its first weeks, is a period during which severe congenital defects can form. That is why the expectant mother should be attentive to her health at this stage of pregnancy. She should avoid taking alcohol, tobacco, and drugs.

After 6-7 weeks, the structure of the unborn child’s heart does not change, it only continues to increase in size. In the first trimester, the organ is located in the neck, later it moves to the chest cavity. Initially, the heart is large in size compared to the entire body of the fetus - approximately 10% of the mass of the embryo; by the end of pregnancy it is about 1%.

Reasons for listening to the heart

Listening to the fetal heartbeat is one of the simplest methods for determining its condition. Determining heart rate helps diagnose the following three main conditions:

#1. Frozen pregnancy.

When an unborn child dies in utero, its heart stops beating. The method for determining heartbeats is not always reliable in the earliest stages of pregnancy - up to 8 weeks.

#2. Malformations of the heart.

If the organ develops incorrectly, the pulse may deviate in one direction or another.

#3. Fetal hypoxia.

The unborn child reacts sensitively to the lack of oxygen, trying to compensate for this condition. Changing heart rate is a method of increasing blood flow to organs.

Methods for listening to the fetal heart

The fetal heartbeat at 20 weeks of gestation and later can be determined using auscultation. For this you need an obstetric stethoscope. It is a hollow tube with a funnel at the end. Heartbeats can be heard from the side where the baby's back is located, closer to his head.

To measure the fetal heart rate, the doctor places the funnel of a stethoscope on the expectant mother’s abdomen, on the projection of the fetal heart. The doctor places the other end of the tube against his ear. To calculate the heart rate, he counts the number of heart beats in 30 seconds, then multiplies the number by 2. The doctor performs auscultation at each visit of the expectant mother, since this method is easy to use, but can help in diagnosing pathology.

During auscultation, the woman should lie on her back. Before taking measurements, the doctor must determine the position of the baby in the uterine cavity. With a cephalic presentation (the baby is head down), heartbeats are heard below the navel on the side, with a pelvic presentation - on the left and right above the navel.

If the child is in a transverse position, heart sounds are heard on the side of the navel. The technique of listening to heart rate using a stethoscope is quite simple, but the doctor must distinguish the work of the organ from the side noise - the intestines and blood vessels of the mother.

Auscultation can be used from (less often from 18), however, in the middle of the second trimester, fetal heart sounds are very quiet. Every day they become louder, towards the end of the period of bearing the baby they can be heard by putting your ear to the anterior abdominal wall.

A more complex method of determining the heartbeat of an unborn child is ultrasound. There are two principles of ultrasound examination. The first of them is transvaginal (the sensor of the device is inserted into the vagina), with which the heart rate can be heard from the 4th week of pregnancy. The second method is transabdominal ultrasound (the study is carried out through the anterior abdominal wall), it helps to determine the heartbeat of the unborn child a little later - from the 6th week of gestation.

Ultrasound allows you to establish not only the baby’s heart rate, but also the anatomical structure of his heart, and detect pathologies and anomalies in the development of the organ. This examination is carried out to all pregnant women during screening; if its indicators are normal, there is no need for additional diagnostic methods.

Fetal echocardiography is an ultrasound diagnostic method that allows you to obtain transverse and longitudinal sections of the heart, observe chamber contractions and valve function. This study also helps to determine the characteristics of blood flow in the great vessels - the aorta, pulmonary trunk, and vena cava.

Echocardiography is an additional method for studying the heart; it is performed only when indicated. These include deviations on standard ultrasound, retardation of intrauterine growth and fetal development, diabetes mellitus and others.

Attention! Auscultation and other methods of examining a baby’s heart cannot help determine his gender; the heartbeats of boys and girls are no different from each other.

Cardiotocography (CTG) is a method for studying the baby’s cardiac function, used with. However, more reliable results can be obtained from 34 to 39 weeks. The principle of its operation is to record the heart rate of the unborn child and uterine contractions relative to each other. As a result, a line with various teeth is recorded on the film. The nature of the recording obtained is used to evaluate the functioning of the fetal cardiac system.

The CTG device consists of two parts - the first registers the fetal heartbeat, the second records uterine contractions. During the examination, the expectant mother should sit or lie down. Cardiotocography is not a mandatory diagnostic method during pregnancy. Indications for its implementation may include pathologies such as intrauterine growth restriction and fetal development, gestational arterial hypertension, and diabetes mellitus.

However, during childbirth, cardiotocography is mandatory. This method allows you to observe the child's reaction to contractions. If there are deviations, doctors can take the necessary measures in time and perform an emergency caesarean section.

Active fetal heartbeat at 7 weeks of pregnancy:

Independent methods of listening to the fetal heart

The easiest way to listen to the fetal heartbeat at home is to ask your spouse or another person to put their ear to the expectant mother's belly. However, this method can only be used from the 30th week of pregnancy, since before that a person will not hear the fetal pulse.

Also, a family member and other close people can use an obstetric stethoscope. The principle of its use is described above; when using it, you need to know the position of the baby in the uterine cavity, otherwise the person will listen not to the baby’s heart, but to the work of the mother’s intestines.

A more reliable, but expensive way to listen to a baby's heartbeat at home is a fetal doppler. It is an ultrasound machine with a speaker that can be used from the 12th week of pregnancy. This device is safe for the baby’s body; it can be purchased in medical equipment stores.

Heart rate norms

Fetal heartbeats appear from the moment the heart is formed - from the 3rd week of pregnancy. At this time, it is equal to the mother's heart rate and is about 80 beats per minute. During the first weeks of life, the heart rate increases by 3 beats per minute every day.

At 7 weeks pregnant, the average fetal heart rate is about 130 beats per minute. It then begins to increase, reaching a peak at . At this stage, the average heart rate of the unborn child is about 175 beats per minute. From the 10th week of pregnancy, the heart rate gradually decreases, reaching 140 beats per minute. This heart rate corresponds to the entire period of pregnancy from 15 to 40 weeks.

The normal fetal heart rate by week is presented in the table:

Week of pregnancy

Average fetal heart rate

Causes of increased fetal heart rate

Tachycardia or rapid fetal heart rate can be the result of a variety of disorders. Sometimes the pathology is caused by diseases of the mother's thyroid gland or taking certain medications. However, much more often an increased heart rate occurs due to pathologies:

1. Fetal hypoxia.

In case of acute fetal hypoxia, which occurs during placental abruption, the heart of the unborn child reflexively increases its activity. This reaction is adaptive; it increases blood flow to the brain and other vital organs. In chronic hypoxia, the heart rate is rarely elevated.

2. Fetal anemia.

This disease occurs due to a decrease in the number of hemoglobin and is accompanied by oxygen starvation. Neural protective factors reflexively accelerate the fetal heart rate, which compensates for this condition. Anemia can occur due to a deficiency of iron, folic acid and vitamin B12 in the mother, or due to hereditary defects in the baby's blood system.

3. Intrauterine infection.

Pathogenic microorganisms can cause circulatory problems, fever and other consequences.

4. Congenital chromosomal pathologies.

Quite often, against the background of fetal developmental anomalies, the heart cannot fully perform its work, which is manifested by a compensated increase in heart rate.

During labor, short-term tachycardia is normal because it reflects the fetal response to contractions.

Reasons for decreased fetal heart rate

The most common cause of rare heartbeats or bradycardia in an unborn child is chronic fetal hypoxia. With a prolonged lack of oxygen, the fetal body compensatoryly reduces heart rate. This phenomenon is observed when the umbilical cord is clamped.

Also, a low heart rate may be a consequence of congenital developmental abnormalities. If the organ is not laid down correctly, it cannot perform its function correctly. Bradycardia is observed with, Patau and other chromosomal abnormalities.

Sometimes bradycardia in the future occurs due to diseases of the mother. A decrease in fetal heart rate is a consequence of arterial hypotension - low blood pressure. Also, the baby’s bradycardia can occur due to compression of the mother’s inferior vena cava by the enlarged uterus. A decrease in fetal heart rate is observed when the mother takes certain medications.

Causes of muffled fetal heartbeats

A weak fetal heartbeat in early pregnancy may be a consequence of congenital malformations of the fetus. However, sometimes this phenomenon is observed normally - with increased body fat in the mother, or when using outdated equipment.

A muffled heartbeat in an unborn child can be observed due to chronic oxygen starvation. Also, difficulties during the study of the baby’s heart rate arise when placenta previa, increased or decreased amount of amniotic fluid. A quiet heartbeat may be due to improper placement of the stethoscope or active contractions during labor.

Few people know exactly when the fetus starts to have a heartbeat. Starting from the fifth week of pregnancy, the heart only pulsates slightly, and by the end of the eighth week it becomes four-chambered and works fully.

As a rule, the first ultrasound examination is done at 12 weeks, but at 5 - 6 weeks a transvaginal ultrasound can be done, which makes it possible to hear the first fetal heartbeat. This process is then monitored by the doctor who is managing the woman’s pregnancy. And to listen to the fetal heartbeat, he uses a special device, which is made of wood, so it transmits sounds quite well.

But the baby’s heart does not always work normally. Slow or too fast work indicates certain disturbances in the child’s development.

Muffled fetal heartbeat

The normal rhythm of the heart of the unborn baby is considered to be 170-190 beats per minute at 9 weeks, and after the eleventh week the number of beats decreases to 140-160 beats. But if the fetus has a weak heartbeat, that is, less than a hundred beats per minute, then it is necessary to carry out treatment aimed at eliminating the problem that caused the slowing of the heart rate.

There are cases when the fetus does not have a heartbeat. This may be caused by the following factors: