Normal fetal heart rate, diagnosis and treatment of abnormalities

When can you hear the fetal heart?

The question of when a fetal heartbeat appears is relevant for every expectant mother, as is such an important point as fetal movement during pregnancy, the norm of which may be different for each woman. The heartbeat can also be heard for the first time at different times.

Women who are interested in how long the heartbeat appears should understand that the fetal heart does not start beating at once. When the formation of this organ begins, part of the tissue that will subsequently develop into the ventricles of the heart performs contractile movements. Of course, the period when the fetal heartbeat is heard on an ultrasound comes later.

The gynecologist will tell you at what week this sound is heard: it can sometimes be heard already in the very early stages. At what hCG level a heartbeat is heard and at what time it is “visible” on an ultrasound also depends on the power of the device used to conduct the study. Using a regular abdominal ultrasound probe, the doctor can hear heartbeats as early as 5 weeks. And with the help of a vaginal sensor, beats can be heard already at 3-4 weeks, that is, immediately after the fetal heart begins to beat.

The heart rate depends on what week the heart beats. It is different at different stages of pregnancy.

• When the period is 6 weeks - 8 weeks, the fetal heart rate is 110-130 beats per minute.
• In the period from 8 to 11 weeks - heart rate can increase to 190 beats.
• Already from 11 weeks the frequency is 140-160 beats.

The table below shows the heart rate at different stages of gestation. It is very easy to understand how many beats per minute the baby’s heart should beat during different periods of pregnancy.

Fetal heart rate table by week:

Those who are interested in the table of fetal heart rate by week by gender of the child should know that both girls and boys have the same heartbeat.

The doctor evaluates not only the fetal heartbeat by week, but also additional factors, such as the child’s activity phase, diseases of the mother and fetus, the time when the frequency is determined, etc.

If the normal fetal heartbeat is disrupted over the weeks, this may be due to various reasons.

How does a cardiotocograph work and what does it show?

This device has the following sensors:

• Ultrasound, which detects the movements of the fetal heart valves (cardiogram);
• Tensometric, determining the tone of the uterus (tocogram);
• In addition, modern cardiac monitors are equipped with a remote control with a button that must be pressed at the moment the fetus moves. This allows you to assess the nature of the baby’s movements (actogram).

Information from these sensors enters the cardiac monitor, where it is processed and displayed on an electronic display in digital equivalent, and is also recorded by a recording device on thermal paper. The speed of the tape drive differs among different types of fetal heart monitors. However, on average, it ranges from 10 to 30 mm per minute. It is important to remember that there is special thermal paper for each cardiotocograph.

example of a CTG tape: above - fetal heartbeat, below - uterine tone values

Why is the heart rhythm abnormal?

If heart rate is less than 120 beats per minute

• The causes of a weak heartbeat in the early stages may be due to various reasons. It can be fixed for a short period of time - up to 4 weeks. At week 6, the embryo's pulse can be 100-120 beats. A pulse of 130 beats also indicates that everything is fine with the baby. But if a very low heart rate is recorded, less than 80 beats, then there is a risk of pregnancy loss.
• If an ultrasound at 12 weeks or more indicates a low heart rate, this may be due to chronic hypoxia of the fetus or its reaction to the umbilical cord being compressed. If the heartbeat is 120 beats per minute, the doctor should tell you what to do, based on the research results.
• Before birth, a weak rhythm may be evidence of acute or chronic fetal hypoxia, as well as compression of the umbilical cord during contractions.

If your heart rate exceeds 160 beats per minute

• In the first weeks of pregnancy, this is usually normal, but in some cases it indicates a placentation disorder.
• After 12 weeks of pregnancy, the fetus may react in this way to its own movements or to the stress experienced by the mother.
• tachycardia in later stages may be a consequence of chronic fetal hypoxia or a reaction to movement or contraction.

Sounds are dull, tones are hard to hear

• If listening is carried out in pregnant women in the early stages, this may indicate that the period is too short, or the study is carried out with a faulty sensor, or the listening device is outdated. This is also possible if the mother is obese . But also hard-to-hear tones in the early stages may be evidence that the baby has a heart or vascular defect.
• After 12 weeks, dull tones can be heard if the mother is obese, as well as with feto-placental insufficiency , presentation (if the placenta is located on the anterior wall), oligohydramnios or polyhydramnios. Sometimes dull tones are recorded if the position of the baby in the womb is inconvenient for listening. However, heart or vascular defects are also possible.
• In late tones, this phenomenon indicates that active contractions have begun or fetal hypoxia .

No heartbeat

• At the earliest stages, the sound of a heartbeat is absent if the period during listening is very short, or an outdated sensor is used. However, sometimes this is evidence that the pregnancy has stopped or an abortion .
• At a period of 12 weeks or more, as well as in the last weeks, the absence of a heart sound can either be evidence of an incorrect site of auscultation or a breakdown of the CTG sensor, or indicate that antenatal fetal death .

How does CTG influence medical tactics?

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The results of the study must be taken seriously. The doctor who evaluates the CTG bears great responsibility. It is for this reason that each film recording cardiac activity must be evaluated by the responsible physician, certified by his signature indicating the time of the study and pasted into the birth history.

A normal cardiotocogram is a sign of correct and careful management of labor.

When receiving a questionable CTG, the doctor has no more than 40 minutes to correct labor activity. At this stage, it is necessary to eliminate all risk factors leading to hypoxia:

1. Stop administering “oxytocin” and prostaglandin-based drugs;
2. Explain to the woman how to breathe correctly during contractions;
3. Determine the position of the fetus and exclude compression of the umbilical cord;
4. Perform an ultrasound to exclude incipient placental abruption;
5. Administer drugs that improve the rheological properties of blood.

Poor CTG is a good reason to change delivery tactics in favor of emergency cesarean section,

or eliminate the causes of acute hypoxia. Ignoring pathological CTG is absolutely unacceptable, because this can cause fetal death.

In other words, CTG is a serious tool in the hands of an obstetrician.

Why determine the fetal heartbeat?

The presence of a heartbeat and the rate of fetal heartbeat are determined during pregnancy for a specific purpose.

To determine that pregnancy is progressing

After the expectant mother takes a pregnancy test and it comes back positive, the woman goes to the hospital to have an ultrasound scan. Modern ultrasound machines make it possible to hear the heartbeat of the embryo already during the first examination - at 4-5 weeks. But if you can’t hear the baby’s heart at the first ultrasound, you shouldn’t panic. As a rule, when the procedure is repeated, you can hear the expected sound. However, sometimes a heartbeat does not appear, and the fertilized egg becomes deformed. This condition is defined as frozen pregnancy . In such a situation, medical termination of pregnancy is performed using special drugs. If such a situation occurs, then the woman is not recommended to become pregnant for about six months after this.

To assess fetal development

There are clear indicators of what is considered normal heartbeat at what stage. That is, a normal heartbeat per minute is determined depending on the period of development of the baby. The embryo's heart reacts to any changes in the world that surrounds it. After all, stress or illness of the mother directly affects children. Also, the rate of heart beats per minute varies depending on the period of activity or sleep of the fetus. The level of oxygen in the air also affects the heart rate. However, any disturbances associated with exposure to such factors are temporary.

If the heart rate is too high for a long time, the doctor may suspect problems with the blood supply to the fetus, so-called fetoplacental insufficiency . As a rule, this condition is chronic. Sometimes, when the child's compensatory capabilities are depleted, the heart rate is too slow. This indicates that the condition of the fetus has worsened. In such a situation, a decision is sometimes made to perform an emergency delivery. The doctor takes into account what the heartbeat should be in which week, and when exactly the pathology appeared, determines the treatment tactics.

Determination of fetal condition during labor

During childbirth, the baby experiences very strong stress, lack of oxygen and compression. If everything goes well, then his heart and blood vessels cope normally with such loads. However, sometimes emergency conditions occur, for example, placental abruption , umbilical cord clamping , in which prompt medical attention is needed.
That is why during childbirth the doctor determines how many beats the heart rate is after each contraction, so as not to miss the development of an acute lack of oxygen.

Timing of planned ultrasound scans during pregnancy and indications for unscheduled examinations

The content of the article

Routine fetal screenings are carried out within the following framework:

• The first screening is from the 10th to the 14th week.
• The second screening is from the 20th to the 24th week.
• The third screening is from the 30th to the 32nd week.

However, most women undergo the procedure more often. The reasons for non-screening ultrasound are the following:

Up to ten weeks:

• The need to confirm the fact of pregnancy and determine the due date.
• There is experience of miscarriage due to miscarriage, habitual miscarriages, missed pregnancies.
• Pregnancy took place through the use of assisted reproductive technology
• There have been negative experiences with fetal pathologies in the past.
• There was a multiple pregnancy in the family.
• Determination of intrauterine or ectopic pregnancy.

After the first ultrasound, you need to undergo an unscheduled examination if you have:

• Nagging pain in the area of ​​the reproductive organs - lower abdomen.
• Presence of bleeding or unusual discharge.
• The size of the uterus is inappropriate for the given period, the belly is too large.
• Suspicion of leaking amniotic fluid.
• The need to control insufficiency (weakness) of the cervix.

You also need to be examined to confirm or refute the conclusions of doctors from previous ultrasound examinations that showed pathologies.

General indications for all three trimesters:

• Bleeding, discharge.
• Stomach ache.
• A uterine size that is not appropriate for the current week is noticed during an examination by a leading gynecologist - then an ultrasound is necessary to exclude an undeveloped pregnancy

What methods are used to determine heart rate?

Ultrasonography

The first method to determine whether the heart rate is normal or not is an ultrasound examination. During an ultrasound, together with an assessment of the heartbeat, the doctor assesses the condition of the placenta and the size of the fetus.

The sounds of the heart are listened to very carefully, and its structure is studied if the woman has already given birth to children with vascular and heart defects. If the mother suffered infectious diseases during pregnancy, special attention is paid to the work and structure of the heart.

If necessary, an ultrasound of the fetal heart is performed during pregnancy. At what time to do an ultrasound of the fetal heart is determined by the doctor. The most optimal time to study echo CG is 12 weeks. But a woman can conduct an echocardiography at her own request to make sure that everything is fine with the child.

Auscultation

This method involves listening to heart sounds using a special obstetric stethoscope. True, the answer to the question of whether it is possible to hear a heartbeat in the early stages with a stethoscope is negative. The period when you can hear with a stethoscope is 18-20 weeks. An experienced doctor can determine a number of indicators using such a device. He will listen to the approximate rate at which the heart beats, determine the clarity of the tones and find the place where they are heard best. The algorithm for listening to the fetal heartbeat and determining heart rate is simple: this can be done using a stopwatch.

But sometimes auscultation with a stethoscope is difficult or even impossible. This is likely if the mother is very heavy, if the placenta is located on the anterior wall of the uterus (in this case, the noise of the vessels interferes), if there is very little or a lot of amniotic fluid.

Cardiotocography (CTG)

This is an informative method with which you can evaluate the fetal heartbeat. This procedure makes it possible to determine the oxygen starvation of the fetus in the early stages and promptly eliminate this problem.

A CTG machine is an ultrasound sensor that sends and receives reflected signals from the heart. In this case, all rhythm changes are recorded on tape. During the procedure, the doctor installs not only the main sensor, but also a uterine contraction sensor, with which you can determine the activity of the uterus. The most modern devices have fetal movement sensors, and sometimes there is a special button so that the woman herself can record the movements.

The entire process of CTG examination takes about 60 minutes. During this period, in most cases, it is possible to record the period of sleep and activity of the fetus. But sometimes there is a need to examine the condition of the fetus throughout the day. Then the sensors attached to the stomach are left for a day.

Heart rate analysis is carried out taking into account the stage of pregnancy at which the study was carried out. The first CTG is performed at 32 weeks. If it is carried out earlier, at 30 weeks or even earlier, the results will be uninformative. When the 31st week passes, a relationship is formed between cardiac activity and fetal motor activity.

Most often, a pregnant woman undergoes this test twice – at 32 weeks and before giving birth. This procedure does not harm either the woman or the baby, so it can be performed as many times as necessary.

A specialist deciphers the CTG tape and compares the results with test and ultrasound data. However, cardiotocography is not a source of definitive diagnosis.

What is a “good” CTG

“Good” CHT is considered if the indicators are as follows:

• Normal heart rate is from 120 to 160 beats per minute;
• when the baby moves, the heart rate increases;
• There is no decrease in heart rate or it is observed very rarely and in small quantities.

The device analyzes these indicators and, based on its results, issues a special PSP index. If the condition of the fetus is normal, then this index is not more than one.

However, it must be taken into account that a variety of factors influence how a child’s heart works. And only a specialist can evaluate them correctly.

Why is a “bad” CTG determined?

• Most often, changes on CTG are determined if fetal hypoxia . An increase in heart rate is characteristic of a condition when the fetus does not have enough oxygen, and the heart is forced to work very intensely.
• When a contraction or movement occurs, the baby's heart rate may slow down, which is not normal.
• Short changes on the tape are recorded if the umbilical cord is pressed against the fetal head. In this case, the results look the same as with oxygen starvation, but the baby feels normal.
• If the sensors were not attached correctly, the results obtained may also be “bad”.

If hypoxia by listening to the fetal heartbeat, the doctor conducts additional studies to confirm or refute the diagnosis. If hypoxia is confirmed, treatment is carried out, or the doctor decides on emergency delivery.

Echocardiography

Echocardiography is used if there is a suspicion of heart defects in the fetus at 18-28 weeks of pregnancy. Using this method, you can determine the structural features of the heart and blood flow. This procedure is carried out in the following cases:

• the expectant mother already has children diagnosed with heart defects;
• infectious diseases were suffered during pregnancy, especially in the first weeks;
• the mother has congenital heart defects;
• the expectant mother is over 38 years old;
• The woman has been diagnosed with diabetes mellitus ;
• intrauterine growth retardation is noted;
• the fetus has malformations in other organs, and there is a possibility of developing congenital heart defects.

This method is used both as a two-dimensional ultrasound and using other modes of an ultrasound scanner: Doppler mode, one-dimensional ultrasound. With this combination of techniques, it becomes possible to carefully study the structure of the heart and the features of blood flow.

Norms of fetal ultrasound indicators in the second trimester in the summary table

Third trimester

The last planned ultrasound examination is the most extensive and consists of measuring and studying the following fetal data:

• BPR - biparietal head size;
• LZR - fronto-occipital size;
• OG - head circumference;
• AB – abdominal circumference;
• DG – length of the tibia;
• DB – length of the femur;
• DP – length of the humerus;
• Height – 430 -470 mm;
• Weights – 1400 – 2400 grams;
• Beclair's nuclei - with normal development less than 5 mm;
• Thickness of placenta;
• The maturity of a child's place;
• Placenta placement, its presentation and the presence of abruption;
• AFL - the amount of amniotic fluid - 1-1.5 l is considered the norm;
• The length of the neck is considered normal to be from 30 to 35 mm.

Is it possible to determine the sex of a child by heartbeat?

Many women at a certain period of pregnancy are actively worried about how to determine the sex of the child by the fetal heartbeat. Indeed, among pregnant women and even among some medical workers, “there is a legend” that such a determination is possible, as well as the assumption that the size of the fetus can help determine who will be born - a boy or a girl.

It is believed that girls' hearts beat faster, and at 13 weeks or later their heart rate is up to 160 times per minute. According to this “belief,” boys’ heartbeat is 135-150 beats. But those who actively ask doctors questions: “How to find out the gender of a child by heartbeat at 12 weeks” or “At what age is this possible”, you need to take into account that this method is not scientifically based. Although there is an opinion that this method is only relevant up to 20 weeks.

The question of how many weeks it is possible to determine the sex of a child in this way is not relevant in principle, and heart rate is not a determining indicator. After all, it is possible to determine whether a boy or a girl is a boy or a girl by frequency only with an accuracy of 50%.

True, there is an opinion that in this case the fetal heartbeat is also important. Some “experts” claim that in boys it is more rhythmic, and in girls it is more chaotic.

There is one more sign: in boys, the heart rhythm coincides with the rhythm of their mother, but in girls it does not. But all these methods have nothing to do with medicine. After all, heart rate reflects the fetus’s ability to overcome a lack of oxygen, and not gender. Therefore, for mothers who begin to “guess” the gender immediately when the embryo’s heart begins to beat, it is better to get a high-quality ultrasound from a good specialist who will help find out the baby’s gender with high accuracy.

Norms of fetal ultrasound indicators in the first trimester in the summary table

Second trimester

The ultrasound report from the 20th to the 24th week contains the following abbreviations:

• BPR – biparietal size of the fetal head;

• LZR – fronto-occipital size;
• BPR/LZR – cephalic index;
• AB – abdominal circumference;
• RS – heart size;
• DG – tibia length;
• DP – shoulder length;
• DB – thigh length;
• OG – head circumference;
• s/b or heart rate - heartbeat;
• IUGR – intrauterine growth restriction;
• DgRK – chest diameter;
• AFI - amniotic fluid index - an indicator of the amount of amniotic fluid;
• ICI - isthmic-cervical insufficiency - the cervix with this pathology is not long enough for full gestation.

Is it possible to hear a baby's heartbeat at home?

Is it possible to hear heartbeats with a phonendoscope? Those who are interested in how to listen to the heartbeat at home can use several methods. You can hear this sound, pleasant for parents, at home using a stethoscope, a portable device - a fetal doppler, and, finally, simply by placing your ear to your tummy.

How to listen to the heartbeat at home will be discussed below. After all, there is no need to visit a antenatal clinic for this. If the expectant mother and her entourage have experience, the heart can be heard earlier. After all, a more experienced woman notices fetal movement earlier during her second pregnancy. The normal heart rate, however, must be monitored by a doctor.

Using a stethoscope

You can listen to the heart using an ordinary obstetric stethoscope. It is necessary to purchase an obstetric tube and use someone's help. Of course, it will not be possible to listen to a fetus at 12 weeks of pregnancy at home. If this person does not have experience, then it will not be possible to hear anything earlier than 25 weeks. But if the fetus is listened to at 30 weeks, then it is much easier to hear the beats. You just need to practice a little and get the hang of it. In this case, it is necessary to clearly distinguish what it is - the pulse, the peristalsis of the pregnant woman, the movements of the fetus, or its heartbeat.

Using fetal doppler

If you wish, you can buy a special device - a fetal doppler. This is a portable ultrasound detector that works like a regular CTG machine, but the image is not captured on film. Sometimes headphones are included so you can hear sounds clearly. With the help of Doppler, you can hear heart sounds starting at 8 weeks. However, it is better to start using this device a little later. It is important that the study itself does not last longer than ten minutes.

The advantages of this device include the ability to listen to the heartbeat in the early stages, as well as ease of use and the ability of a woman to do this without help.

The disadvantages of using Doppler are its high cost and limitations in use. In addition, this device should not be used without measure.

Putting your ear to your stomach

Sometimes you can hear the heart just by putting your ear to your tummy. This is possible in the last weeks of gestation. However, a positive result can only be obtained if the expectant mother does not have too much fat.

You need to listen to the heart in a certain place in the abdomen, depending on how the baby is positioned. If it lies head down, then you need to listen to the heartbeat below the woman’s navel. If the baby's head is at the top, then it is advisable to listen to the tones above the mother's navel. During multiple pregnancies, the heartbeat of each fetus can be heard in different places.

Norms of fetal ultrasound indicators in the third trimester in the summary table

conclusions

Thus, heart rate is a very important indicator of child development. The pulse rate is monitored by a doctor during pregnancy. Expectant mothers should know that severe heart pathologies are very rare, and in most cases, babies are born healthy. But, nevertheless, it is important to regularly undergo all tests and monitor your heartbeat. The rate of beats per minute in women and children are important indicators, and the doctor takes this into account. But the expectant mother herself should be very careful about her own health and “listen” to the baby.

Who will be born: modern ways to find out

There are 2 reliable ways to find out who will be born in a family.

The first is ultrasound. Already at the second screening, that is, from the 12th week, you can get an answer. But errors are also possible - the method guarantees the correct result in 97% of cases.

The second method is amniocentesis. This invasive technique is carried out according to strict indications and not to find out who will be born to a couple, but to diagnose certain diseases in the baby. And sex determination is only an additional option of amniocentesis. But this is currently the only method that gives a 100% correct result.