Ultrasound of pregnancy fetal heartbeat. Which method of diagnosing fetal heartbeat is the most informative? Methods for determining heart rate - what devices are used to listen to the heart rhythm

Birthday
21.07.2019

It is the heart rate that characterizes big picture about the child's health status. If various unfavorable situations arise, this indicator instantly changes, thus signaling a problem.

That's why The child’s heart function is constantly monitored: during the 9 months of pregnancy, mothers look after him, and during childbirth - doctors.

Also, the fetal heartbeat is important indicator of a favorable pregnancy. The nature of the unborn baby's heartbeat and its frequency give doctors reason to evaluate general state child.

It is important to note that heart development is considered quite complex natural process. The formation of the fetal heart begins already in the fourth week of pregnancy.

The first pulsating contractions in little heart appear around the fifth week of pregnancy. At the eighth to ninth weeks, the heart already becomes normal four-chambered, has two ventricles and two atria.

Since the fetus receives oxygen from the mother and is deprived of the ability to breathe on its own, his heart has some peculiarities. They are expressed in the presence of the arterial (botallian) duct (this is a vessel connecting the pulmonary artery and the aorta) and the oval window (it is located between the right and left atrium).

This cardiac structure is significantly different from the structure of the adult heart. Due to the fact that the fetus has such a heart structure, all its organs and systems receive oxygen in the required volume. After the birth of the child, the oval window closes and the ductus arteriosus subsides.

How do you know everything is okay?

To assess fetal heart activity in modern medicine the following procedures apply:

  • Ultrasound (ultrasound examination);
  • listening to the fetus (auscultation);
  • echocardiography;
  • cardiotocography.

The most popular method for assessing the fetal heartbeat is ultrasound.

It is necessary to know the fact that with the help ultrasound examination The fetal heartbeat is detected at the very beginning of pregnancy.

It is considered normal if with transvaginal ultrasound(in which the sensor of the device is inserted directly into the vagina), the heartbeats of the embryo are noticed in the fifth or sixth week of pregnancy.

A with transabdominal ultrasound(when the sensor is placed on the belly of the expectant mother) - somewhere around the sixth or seventh week.

Monitoring your heart rate

In the first trimester, that is, up to thirteen weeks, heart rate changes. For example, from the sixth to the eighth week the frequency of such contractions is about 110-130 beats per minute, from the ninth week to the tenth - 170-190 beats.

And from the eleventh week until birth, the heart rate fluctuates around 140-160 beats per minute.

These kinds of changes in heart rate are caused, first of all, by the development and formation of various functions of the autonomic nervous system. After all, she is the one responsible for the work of various internal organs future baby.

That's why, if the frequency of such contractions in the embryo decreases to 85-100 beats per minute, or vice versa, this the indicator exceeds 200 beats, this is an unfavorable sign for establishing current and future diagnoses.

In such situations, it is necessary to undergo a course of treatment, as a result of which the reasons for the decrease or increase in heart rate will be eliminated.

If the length of the embryo exceeds 8 millimeters, and there are no heartbeats, a preliminary diagnosis of “” is often made. To confirm this diagnosis, a repeat ultrasound examination is necessary after five to seven days. According to its result, this diagnosis is confirmed or a new one is made.

Carrying out ultrasound examinations in the second and third trimesters of pregnancy is that the obvious object of study is the location of the fetal heart in its chest.

When scanning transversely, the child’s heart should be located on the left, occupying a third of the volume of the entire chest. The heart rate during this period of pregnancy is approximately 140-160 beats per minute. The nature of the fetal heart contractions is also assessed (it can be rhythmic or non-rhythmic).

In later stages of pregnancy factors such as fetal activity and physical activity directly affect the heart rate of the unborn baby expectant mother, her stay in heat or cold, her exposure to various diseases.

To determine the presence of heart defects It is necessary to conduct studies of the “four-chamber section” in the future baby. In this ultrasound image, doctors are able to view all four chambers of the heart at the same time.

A standard ultrasound examination of a “four-chamber slice” of the heart can immediately detect about 75% of heart defects in the fetus. If a suspicion of a heart defect in the fetus is detected, an additional study is performed - fetal echocardiography.

And finally should be emphasized again that the study of the fetal heartbeat is mandatory throughout all nine months of pregnancy and especially during childbirth. This allows you to correctly assess the condition of the unborn baby, carry out the necessary course of treatment in a timely manner and decide on the timing and method of delivery.

The birth of a new life is a great mystery. Today, doctors have devices at their disposal that allow them to “look” into the intrauterine world, and yet we do not yet know all the intricacies of the development of the future person, and we can judge the baby’s condition mainly only by the heart rate (HR). Expectant mothers listen to themselves with anxiety and trepidation, waiting with bated breath for the results of an ultrasound or CTG - is everything okay with the baby? Research protocols usually contain different meanings: A baby’s heart is constantly developing, so fetal heart rate rates can vary significantly from week to week.

Fetal heart rate in the first trimester

The embryo's heart is formed at 4-5 weeks of pregnancy. And already at 6 weeks, the fetal heartbeat can be “heard” using a transvaginal ultrasound sensor. During this period, the baby’s heart and nervous system are still immature, so in the first trimester there are standards that allow the doctor to monitor the development and condition of the child. Fetal heart rate values ​​by week are given in the following table:

Please note that from 5 to 8 weeks inclusive, the average heart rate and their permissible deviations are given at the beginning and end of the week (increase in heart rate), and from the 9th week of pregnancy. For example, a fetal heart rate at 7 weeks will be 126 beats per minute at the beginning of the week and 149 beats per minute at the end. And at 13 weeks, the fetal heart rate, on average, should be 159 beats per minute; indicators from 147 to 171 beats per minute will be considered normal.

Fetal heart rate in the second and third trimester

It is believed that from 12-14 weeks of pregnancy until birth, the baby’s heart should normally make 140-160 beats per minute. This means that the fetal heart rate at 17 weeks, at 22 weeks, at 30 and even at 40 weeks should remain approximately the same. Deviations in one direction or another indicate that the baby is not well. If the heartbeat is rapid (tachycardia) or slow (bradycardia), the doctor will first of all suspect intrauterine fetal hypoxia. Tachycardia indicates mild oxygen starvation baby, which appears as a result of the mother’s long stay in a stuffy room or without movement. Bradycardia indicates severe hypoxia resulting from fetoplacental insufficiency. In this case it is necessary serious treatment, and sometimes emergency delivery via cesarean section (if long-term therapy does not produce results and the condition of the fetus is steadily deteriorating).

At 32 weeks of pregnancy and later, fetal heart rate can be determined using cardiotocography (CTG). Along with the child’s cardiac activity, CTG records uterine contractions and the baby’s motor activity. On later pregnancy This research method allows you to monitor the condition of the child, which is especially important for pregnant women suffering from fetoplacental insufficiency.

There are other causes of fetal heart rhythm disturbances: diseases of the pregnant woman, her emotional or nervous overexcitation, physical activity(for example, gymnastics or walking). In addition, the child's heart rate depends on his motor activity: during periods of wakefulness and movement, the heartbeat increases, and during sleep small heart beats less often. These factors must be taken into account when studying fetal cardiac activity.

Based on the baby's heartbeat in the uterus, a gynecologist can determine whether the baby is receiving enough oxygen and what its general condition is.

Based on the baby's heartbeat in the uterus, a gynecologist can determine whether the baby is receiving enough oxygen and what its general condition is. In the early stages of pregnancy, the baby’s heartbeat can only be heard using special devices, while from the middle of the second trimester, the doctor listens to the heart with a wooden tube using an obstetric stethoscope.

Young expectant mothers are concerned about the question: when does the fetus begin to have a heartbeat? The pulsation of the heart in the unborn child begins already on the 21st day after conception, the frequency of its contractions differs by different weeks pregnancy.

Normal fetal heart rate at different stages of pregnancy

With each week of development of the embryo in the uterine cavity, its heart rate also changes, which is caused by the progressive development of the autonomic nervous system, which is responsible for the functioning of the heart. Below is a table of fetal heartbeats by week of pregnancy.

At the 5th week of gestation, the heart rate of the unborn child is approximately the same as the mother’s heart rate, that is, 80-85 beats/min. Over the course of a month, this figure increases by several beats every day, so by the end of the 1st trimester of pregnancy, the child’s heart rate is 170-175 beats/min.

Starting from the 15th week of pregnancy until the end of the entire gestation period, the gynecologist regularly at each appointment antenatal clinic checks the functioning of the child’s heart in the womb - by listening with a stethoscope through the anterior abdominal wall, using ultrasound, and a portable Doppler. From the 15th week of pregnancy, normally the number of fetal heart beats per minute should not exceed 160-170 beats/min; if these figures are higher, then one can suspect the onset of oxygen starvation in the baby, and if the heart beats less than 130 beats/min, then they speak of acute hypoxia, which can threaten the development and even the life of the child. Strict control of the baby’s heart rate is also necessary during the process of delivery, especially during contractions and pushing; normally 140-160 beats/min. There are indications that require continuous monitoring of the baby’s heartbeat during childbirth CTG device, These include:

What should you pay attention to when listening to the fetal heart?

The formation of the heart in an embryo begins at the earliest stages of embryogenesis, and the work of this organ is an important indicator of the development of the unborn child and his health. Listening to the fetus’s heart rate is necessary throughout pregnancy and during childbirth, since these indicators suggest various pathologies in the child’s body. early stage their development.

When can a fetal heartbeat be heard on an ultrasound? Despite the fact that the pulsation of the heart rudiment in the embryo begins at 21 days, on ultrasound it is possible to listen to heartbeats only at 6-7 weeks of gestation, since at this period the hollow tube begins to transform into a full-fledged four-chamber organ with two ventricles and two atria.

When listening to the heart of an unborn child, pay attention to the following indicators:

  1. Heart rate - a heart contraction of more than 185 beats/min is called fetal tachycardia, less than 100 beats/min is called bradycardia. Both of these conditions are not normal and require clarification of the cause. The fetal heart rate should not exceed 170 beats/min in the second and third trimesters.
  2. Heart sounds are normal healthy child, which develops fully in utero, the heart sounds are clear and ringing; in the presence of defects or developmental anomalies, the contractions are not heard clearly and are blurred.
  3. Heartbeat- in a healthy fetus developing according to the gestational age, myocardial contractions are repeated rhythmically at regular intervals. In case of acute hypoxia or anomalies in the development of the heart valves, an arrhythmia, a “gallop” rhythm, can be heard.

Methods for listening to a baby's heartbeat in the womb

There are several ways to listen to the heartbeat of the fetus in the uterus, depending on the stage of pregnancy.

Ultrasound

Starting from the 5th week of pregnancy, it is possible to evaluate the heart function of the unborn child only using an ultrasound sensor - transvaginally and transabdominally. In the early stages of pregnancy, ultrasound determines whether there are heart contractions, whether the embryo is developing, and how many beats per minute the myocardium pulsates. From 12 weeks to 20 weeks, the doctor evaluates not only the heart rate, but also the location of the organ, the presence of all chambers, and the functioning of the heart valves. It is at this stage of gestation that most heart defects are detected in the fetus.

Stethoscope

An obstetric stethoscope is used to assess the parameters of cardiac muscle contraction after the 20th week of pregnancy. At each appointment at the antenatal clinic, the doctor first determines the location of the baby’s head and its position in the uterus, and then places a tube on the mother’s anterior abdominal wall and listens to the fetal heart sound. From the second half of pregnancy, you can also use a stethoscope, but it is rarely used in obstetrics. During childbirth, the heartbeat is listened to with an obstetric stethoscope every half hour, and attention must be paid to heart sounds before and immediately after contraction.

Cardiotocography (CTG)

From the beginning of the third trimester of pregnancy, the parameters of the fetal heartbeat are assessed using CTG at least once for each pregnant woman. During childbirth, this is a mandatory procedure that shows not only the number of heart beats per minute in the child, but also records the reaction of the fetal heart muscle to each contraction.

Listening to your baby's heartbeat by week

At what week of pregnancy can the fetal heart rate be calculated? The only way to do this in the early stages is only with the help of an ultrasound machine. If at 6 weeks there is no heart pulsation on the monitor screen, then there is a possibility that the pregnancy has frozen. In such situations, the woman needs to be re-examined on another device.

At what week can fetal heartbeats be heard through the abdominal wall? Hear the baby's heart beat through maternal belly It is possible already from the 20th week of pregnancy by applying an obstetric stethoscope to the anterior abdominal wall, but first you need to determine the location of the fetus in the uterus and its position in order to know which side and at what height to apply the tube, otherwise nothing will be heard.

Sometimes, with the help of an obstetric stethoscope, it is not possible to listen to the baby’s heart - this may be due to certain conditions:

  • multiple pregnancy;
  • polyhydramnios;
  • heart defects in the unborn child;
  • overweight and swelling in a pregnant woman;
  • attachment of the placenta to the anterior abdominal wall.

IN similar situations Another method of listening to fetal heart parameters is used. If, during an ultrasound examination, the doctor suspects heart defects in the unborn child, then an echocardiogram of the fetus is additionally prescribed; the procedure will be informative from 20 to 28 weeks of pregnancy. Echocardiography allows you to study in detail all parts of the child’s heart, assess blood flow and valve function, this procedure is mandatory research for expectant mothers over 35 years of age and for those pregnant women who have already born children with heart defects.

Starting from 28-30 weeks, all expectant mothers are prescribed a CTG procedure; a special sensor is attached to the anterior abdominal wall, which records the fetal heartbeat parameters over a certain period of time. Repeated implementation of this procedure is required for women with complicated pregnancy, namely:

  • late toxicosis;
  • the presence of scars on the uterus after surgery and cesarean section in the past;
  • aging of the placenta ahead of schedule;
  • chronic diseases in the expectant mother;
  • decrease or increase in quantity amniotic fluid;
  • intrauterine growth retardation;
  • post-term pregnancy beyond 42 weeks.

CTG indicators are assessed on a 12-point scale: 9-12 points - the child’s normal condition, he receives sufficient quantity oxygen and develops fully, 6-8 points - there are signs of oxygen starvation, CTG should be repeated every other day and, if necessary, prescribe treatment for the pregnant woman, 5 points or less - there is a threat to the child’s life, he suffers from acute hypoxia, the woman needs to undergo C-section. When performing CTG, the basal rhythm and its changes when the child moves are determined. Normally, the first heart rate indicator should be 130-160 beats when the fetus is at rest and up to 190 beats when the fetus moves. Rhythm changes show how much heart rate parameters deviate on average from basal values; normally in a healthy fetus it is no more than 5-25 beats/min.

How to listen to the fetal heartbeat yourself at home?

Many pregnant women are interested in whether it is possible to listen to the baby’s heart at home? This is quite difficult, especially in the early stages of pregnancy. Starting from the 25th week, a stethoscope can be applied to the abdomen, so the mother can hear her baby’s heart beating. Future dad can hear the baby's heartbeat from the beginning of the third trimester of pregnancy by putting his ear to his wife's belly. In the first trimester, a woman can independently listen to the baby’s heart using modern fetal dopplers.

How to determine gender by heartbeat?

There is a theory that the number of heartbeats per minute in a baby in the womb can determine its gender - as if boys' hearts beat less often than girls'. This fact has not been scientifically confirmed, although an ultrasound did reveal that in a male fetus the heart beats evenly and rhythmically, while in girls it is somewhat chaotic. Heart rate can change with the baby's movements, changes in his body position in the uterus and stress in the mother, so by counting the number of heartbeats of the baby, one can only assume one gender or another.

Assessing the baby's heart rate parameters in the womb is an integral part of monitoring the normal course of pregnancy. Based on the nature and frequency of the child’s heartbeats, the doctor may suspect disturbances in its development and the presence of complications in the expectant mother.

When a pregnant woman visits an antenatal clinic, the doctor determines the fetal heartbeat. This necessary examination, which allows you to judge the state of a small life. This parameter changes, and in different periods As the child develops, heart contractions slow down or increase in frequency.

The fetal heart rate by week usually ranges from 120 to 160 beats per minute during the prenatal period. These are echographically measurable numbers. The normal range of heart rate should fluctuate during pregnancy, and from 6 weeks increases to approximately 170 beats by the 70th day of the baby's development and decreases to 130 beats by the due date.

Fetal heart rate chart by week.

Age or size of the fetus Ud. per minute
Embryo 2 mm 75
Embryo 5 mm 100
Embryo 10 mm 120
Embryo 15 mm 80–85
5 weeks 80–103
6 weeks 103–126
7 weeks 126–149
8 weeks 149–172
9 weeks 155–195 (average value 175 bpm)
12 weeks 120–180 (average 150 beats per minute)
After 12 weeks 120–160 (average 140 beats per minute)

The above describes how the heart rate of the unborn baby changes in the first and second trimesters. During the third trimester, this figure is relatively stable. FHR (fetal heart rate) slows down slightly in the last (third) trimester before birth, but it is still about twice that of an adult. SBP must be monitored during childbirth. The heart rate of a child during full-term pregnancy during labor is about 140 beats per minute; while the heart rate in premature babies is 155 beats.

It is important to know that you can hear the fetal heart with a stethoscope from 20–24 weeks. It depends on the position of the child, the amount amniotic fluid and the nature of the tissues of the mother's abdomen. If the fetal heartbeat is normal, the chance of miscarriage is very low. A girl or boy's heart rate from 100 to 160 is considered normal. If the child’s heartbeat is not heard within 2-3 days, monitoring by ultrasound using Doppler ultrasound is necessary.

Unusually low, high or weak SBP is one of the main signs of hypoxia (lack of oxygen). Some pathological processes in the placenta or in the umbilical cord with excessive physical activity mother, mental stress, genetic problems or other complications can lead to rare or frequent SBP. Hearing and counting the fetal heartbeat from 100 to 180 is considered normal if additional studies do not indicate pathology.

Heart rate and fetal age

As you know, pregnancy is divided into three trimesters. Wonderful trip The unborn child from conception to birth is divided into three stages. Depending on mom's weight, baby's position, and the location of the placenta, you may be able to listen to the heartbeat with a stethoscope from about halfway through your pregnancy. With the help of ultrasound technology, the fetal heartbeat can be heard as early as 8 weeks. Sometimes the heartbeat is weak or inaudible even with Doppler at the end of the first trimester, but this is considered acceptable.

The embryo's heart begins to contract from day 35 of pregnancy. SBP is faster than an adult's heartbeat. Initially, during the 5th week, its frequency may be almost the same as the mother's heart rate (80–85 beats per minute). Then it grows at an amazing rate: about 3 beats per minute a day before the start of the second month of pregnancy. Then it becomes stable again: about 150 beats per minute (on average) for about 12 weeks.

The normal fetal heart rate range after week 12 is 120–160 beats per minute. SBP is sometimes used to estimate fetal age based on heart rate. There is a formula: embryonic age in days = SBP x 0.3 + 6.

A pregnant woman needs to know that the heart rate of her unborn child changes naturally with her movements: during rest and during various physical activities. It is normal for the SBP to change at different times during the day. You can hear your baby's heartbeat at home using a stethoscope. But in any case, it is better to consult a doctor if there is any doubt.

People believe that using heart rate you can predict the gender of the child. If the heart rate is more than 140 beats per minute, then this indicates a girl, and a slow heart rate suggests that a boy will be born. The basis for this is supposedly the girl's fast metabolism. This is not scientifically substantiated, and in practice different results are visible. Gender cannot be predicted using heart rate, so don't believe in old wives' tales.

Development of the cardiovascular system

For 4 weeks During pregnancy, a separate vessel is formed in the embryo, which then turns into the heart and circulatory system. In the early stages, the heart resembles a tube, which then twists and divides, eventually forming the heart and its valves. At 5 weeks of pregnancy, the embryo's heart begins to contract spontaneously, although the woman does not hear it.

At 6 weeks The baby's heart beats 80 times per minute and has four hollow chambers, each with an inlet and an outlet to allow blood to flow freely. In just two weeks, the heart rate will increase to 150 beats per minute. This is approximately twice as fast as a pregnant woman's heart rate.

For 9–10 weeks. The baby's heart rate is approximately 170 beats per minute. Neither the pregnant woman nor the doctor hears this during examination, but during an ultrasound, the device will calculate the exact number of beats per minute and even reproduce it.

At 11 weeks it is carried out expert ultrasound which will confirm that the fetal heart is healthy or has birth defects. This diagnosis during pregnancy helps doctors decide whether to continue the pregnancy.

From 12 weeks, the baby’s bone marrow begins to function, producing blood cells. And at 17 weeks. The brain begins to regulate its heartbeat in preparation for life in outside world. Until this moment, the heart was beating arrhythmically. By the end of the second trimester, capillaries (the smallest blood vessels) and fill with blood.

The baby's circulatory system continues to gradually grow, so that by 40 weeks he is ready to take his first breath outside the womb.

Evolution during pregnancy

Although the myocardium begins to contract 20 days after fertilization, this is first observed on ultrasound at approximately 6 weeks of pregnancy. The frequency of these contractions is from 100 to 120 beats per minute.

During a normal pregnancy, the fetal heart rate is regular, but fluctuations from approximately 5 to 25 beats per minute are allowed.

A girl's or boy's steady heart rate is one of the most useful indicators because it is proof that the pregnancy is going well. Therefore, when the fetal heart rate slows down, it is natural to think about the child’s suffering.

SBP and self-abortion

Are fetal heart rate and threat of abortion related? From about 6 to 9 weeks, the fetal heart produces a heart rate of 160 to 180 beats per minute. Over time, as a child's brain grows, the heart rate gradually drops to 110 to 160 beats per minute.

The fetal heart rate may be higher or lower depending on gestational age. This is either a passing phenomenon or a sign that the pregnancy is not sustainable and miscarriage is inevitable. The child reacts to all processes occurring in the mother’s body, so the fetal heartbeat may change. An abnormal heart rate may mean the fetus is not getting enough oxygen or may indicate other problems.

Most miscarriages occur in the first seven weeks of pregnancy due to chromosomal abnormalities. In fact, studies have shown that the likelihood of miscarriage increases when the baby's heart rate is less than 100 beats per minute at 6.2 weeks of pregnancy or less than 120 beats per minute at 6.3 to 7 weeks.

If a pregnant woman feels a decrease in fetal movements at home, she should consult a doctor. An important examination - measuring the fetal heart rate - must be carried out at every visit to the antenatal clinic.

Article publication date: 02/08/2017

Article updated date: 12/18/2018

From this article you will learn: at what time does the fetus’s heart begin to beat, what should be the normal heart rate (HR) during different periods of intrauterine development, and whether the sex of the child affects this. Possible deviations from the norm and their meaning.

The heart is one of the first organs that not only develops, but also fully functions from the first weeks of intrauterine development. Therefore, heartbeat recording is used as a reliable criterion for assessing the condition of the fetus:

  • if the heart contracts, this indicates that the fetus is alive;
  • does the heart rate (heart rate) correspond to the normal parameters for different terms pregnancy;
  • determine intrauterine pathology by the nature of heart rate deviations from the norm and take measures aimed at preserving the life of the child.

Fetal heart rate is one of the most important indicators its health and development from 5–6 weeks of pregnancy until birth. The most important advantage of this parameter is that not only a specialist can evaluate it using special methods(auscultation, ultrasound, cardiotocography). Even future mom or anyone can listen to the child’s heartbeat by placing an ear, a stethoscope, or a portable sensor that connects to a smartphone or other gadget to the desired points in the abdomen. But it is better to entrust the final assessment of this parameter only to a specialist - an obstetrician-gynecologist.

When can you hear the first heartbeat, and how important is it?

The timing of the onset of heart formation and the appearance of its contractions varies. The first correspond to 2–3, the second 4–5 weeks of intrauterine development, regardless of the sex of the child. But in order to record the heartbeat (HR), and even more so to examine the heart at this time, high-precision special ultrasound equipment is needed. Therefore, before 5–6 weeks of pregnancy, fetal heart rate is not a suitable parameter for assessing fetal development.

If the pregnancy is progressing normally, it is enough to do a standard ultrasound examination through the abdominal wall once after 5–6 weeks to see where the embryo is located (in the uterus or outside its cavity) and to verify its viability by the presence of heartbeats. It is not necessary to count them, since this information is so early stage development is of no value. It becomes relevant starting from 10 weeks until the end of pregnancy and childbirth.

If pregnancy proceeds with abnormalities or there is a need to evaluate the heartbeat (HR) at the earliest stages, this can be done at 4 weeks using the transvaginal method (ultrasound through the vagina). But more suitable method in such a situation, a blood or urine test for the level of a special pregnancy hormone is considered - human chorionic gonadotropin human (hCG). If the fetus of either sex develops normally, its concentration will double every 2-3 days by 10 weeks (the norm at 5-6 weeks is 1000-3100 mIU/ml).

Fetal heart rate norms

The heartbeat of a healthy fetus of either sex can be characterized by the following signs:

  1. Regular – occur at approximately equal intervals of time.
  2. Rhythmic - the rhythm cannot be constantly monotonous; periods (several seconds or minutes) of slowing down or accelerating are possible when the position of the pregnant woman changes or the child actively moves. But they are always of the correct nature, replacing each other for a short time. Only isolated non-rhythmic interruptions (extraordinary contractions or pauses) that disrupt the regular rhythm are acceptable.
  3. Normal frequency is the most important parameter, reflecting not only the state of cardio-vascular system, but also the child’s body in general. In general, heart rate remains almost the same throughout the entire prenatal period and does not depend on gender (130–170 beats/min), but norms are provided for each stage of pregnancy. They are shown in the table below.
Fetal age (by week) Heart rate (beats/minute)
4–5 90–115
6–7 105–130
8–9 125–150
10–11 130–160
12–13 135–170
14–15 140–180
16–17 135–170
18–19 130–165
20–21 140–170
22–23 125–160
24–42 120–160

The heart rate does not depend on the sex of the fetus - its rate is the same for boys and girls.

How and with what you can listen

Registration of fetal heartbeats is possible by listening to them and graphically depicting them (like an electrocardiogram). The following methods are used for this:

  1. Auscultation - listening with the ear.
  2. Ultrasound (echography).
  3. Cardiotocography.
  4. Sensors for independent use using gadgets.

1. Auscultation - listening with the ear

Auscultation is the direct listening to the fetal heart sounds through an obstetric stethoscope (a special tube that obstetricians use to listen to the heart). For these purposes, you can also use a regular phonendoscope or put your ear to your stomach at the right points:

  • If the head is facing down to the pelvis, and the back is located on the right, you need to look for the heartbeat in the right parts of the abdomen below the level of the navel. With the same cephalic presentation, but with the back turned to the left, they are heard in the left half below the navel.
  • If the head is located at the top of the abdomen and the buttocks are facing the pelvis ( breech presentation): with the back turned to the left, listen in the left half above the navel, if the back is on the right - in the right half above the navel.
  • With transverse and oblique positions of the fetus (regardless of its gender), which happens in the second and early third trimester of pregnancy, it is difficult to find a point for listening. More often it is located at the level of the navel to the left or right of it.

Click on photo to enlarge

Auscultation is the simplest and most sufficient informative method assessment of fetal heartbeats. But it also has disadvantages:

  • requires skills to find the right point;
  • it is necessary to be able to distinguish between the heartbeats of the mother and the fetus (in the fetus they are twice as frequent and do not correspond to the pulsation of the mother’s blood vessels);
  • with the help of the fetus can be heard only from 27–28 weeks of pregnancy.

2. Ultrasound – echography of the heart

Ultrasound examination is a convenient and informative method for assessing heartbeats, allowing you not only to hear them, but also to directly see and record them. It can only be carried out by a specialist: an obstetrician-gynecologist or an ultrasound diagnostic doctor. IN in a planned manner Every pregnant woman goes through this diagnosis 3 times: at 10–12, 21–23, 31–32 weeks. If necessary, ultrasound can be done as many times as needed, and at an earlier date.


Heart region highlighted in orange

3. Cardiotocography

A type of ultrasound examination that involves only listening to sounds and graphically recording fetal heartbeats (like an ECG) without a visual image of the heart is called cardiotocography. The main advantage of the method is that it allows you to record the child’s cardiac activity even during labor during labor. At the same time, there is a synchronous graphic recording of the heart rate and the force of contractions of the uterus, which makes it possible to assess the blood circulation in the umbilical cord when the uterus is in good shape.

Another advantage of cardiotocography is that it can be carried out for as long as the situation requires (more than an hour). And although only a doctor has the right to evaluate its results, the pregnant woman herself can roughly determine how her baby’s heart is beating, since she hears these heartbeats during the study. Carrying out CTG before 20–21 weeks can be problematic, but possible.

Sensors for do-it-yourself use

There is an alternative type of cardiotocography that can be performed independently by a pregnant woman at home. For this there are special devices– sensors for individual use. They look like a small plastic box the size of mobile phone. By installing this sensor in necessary points for listening on the stomach (they are described in the section of this article “auscultation - listening with the ear”) and by connecting via a cable to a gadget that has an operating system, you can hear the sound of heartbeats and see their graphic recording.

Deviations from the norm, what they talk about

The main heartbeat parameter that is used to assess the intrauterine pathology of a fetus of any sex is the heart rate. Increased heart rate - more frequent, but less dangerous look violations than slowing down.

An increased rhythm, regardless of the sex of the child, signals a threatening or emerging intrauterine hypoxia(oxygen starvation and circulatory failure) with:

  • disruption of the structure and blood circulation in the placenta, as well as any of its pathologies accompanied by placental insufficiency;
  • low hemoglobin levels (anemia) in the mother or fetus;
  • heart and other defects;
  • threat of miscarriage and bleeding;
  • intoxication and elevated temperature bodies of a pregnant woman;
  • umbilical cord pathologies (short, long, torsion, knots);
  • brain pathology accompanied by increased intracranial pressure The child has.

A persistent slowdown in heart rate compared to the norm described in the table in the section “What should they be normally” indicates:

  • severe intrauterine pathology;
  • severe fetal hypoxia;
  • metabolic disorders in the body of mother and child;
  • developmental defects and heart diseases;
  • overdose of beta blockers in a pregnant woman;
  • elevated levels of potassium in the blood.

Development of intrauterine fetal hypoxia. Click on photo to enlarge.

A short-term slowdown (for a few minutes) of the heartbeat can be caused by a pregnant woman staying in a supine position for a long time, which leads to compression of the pelvic vessels and vena cava.

Simple doesn't mean bad. This rule applies to the assessment of fetal heartbeats. Despite the simplicity of determining this indicator, its value is no less than the results of other methods of intrauterine diagnostics.