- How the fetal heart is formed – the first contraction
- What happens next
- When to start measuring the heart rate
- Why do measurements of heartbeat
- What abnormalities exist?
- Causes of abnormal heart rate
- Congenital heart abnormalities
- Ways to measure heart rate – ultrasound
- CTG (cardiotocography) and auscultation
- Ways to hear the fetal heartbeat yourself
The main indicator of the viability of the tiny organism at the onset of pregnancy is the baby’s heartbeat. Its characteristics unambiguously signal the condition of the embryo, whether it receives enough oxygen and other substances. That’s why the work of the future baby’s heart is under constant control, because any deviations in its standard rhythm may indicate problems with the pregnancy.
Such changes may also be characteristic of serious pathologies that arise in the developing body. Therefore, the woman herself preparing to become a mother, and the doctor who leads her pregnancy, should constantly monitor the heartbeat of the child in the abdomen of the expectant mother. It is important not to miss routine examinations, including ultrasound, which allow the most accurate determination of all characteristics and parameters of the heart of a little man.
How the fetal heart is formed – the first contraction
Recent studies by German scientists have made it possible to understand how the embryonic heart is formed and develops, and why at an early stage the baby’s heartbeat can already be heard and even visually observed when examined using an innovative technique. It is known that in the fourth week of pregnancy a hollow tube is formed around the embryo, the purpose of which is to become the primary circulatory circle.
During the next week, a bend forms on the tube, where the first contraction occurs, which will then be heard as the baby’s heartbeat in the womb. Special cells are responsible for the formation of the bends, which, when attached to the cells of the primary tube, “drag” them to the right area. Researchers have found that this process depends on a chain of chemical reactions, the tension of the tube tissue also plays an important role in the formation of the heart. The bends can fail to form if it’s not great enough.
What happens next
As time passes, the unborn child’s heart becomes more and more like an adult’s heart. By the sixth week, the interventricular septum forms and begins to grow, immediately followed by the interatrial septum. The fetal heart becomes almost adult-like by the eighth week of pregnancy.
You can not say that it is completely identical with the adult, because the oxygenated blood comes to the baby is not from the lungs, and from the mother – at this time, he is not yet breathing on their own, although the baby’s heartbeat is already clearly visible. At this stage, all the ventricles and atria function as a single hollow organ, and blood flows from one atrium to the other through the oval open window. This is what the special opening in the interatrial septum looks like. When the newborn baby takes its first independent breath, it will close immediately after delivery.
When to start measuring the heart rate
The baby’s heartbeat at 6 weeks’ gestation occurs at a rate of 60 beats per minute. By this point, it consists of four hollow chambers with separate entrances and exits for the passage of blood. After two weeks, the baby’s heart rate increases sharply and can reach 150 beats in 60 seconds. This rate is considered normal, even though it is twice that of the mother herself. The frequency of the baby’s heartbeat at 9-10 weeks of pregnancy is very high – the little man’s heart beats at a frequency of 170 beats per minute.
From the 35th day of pregnancy, the baby’s heart shows itself by contracting. Its heartbeats are also detected at earlier stages of a woman’s pregnancy. Answering the question on what term the baby’s heartbeat can begin to be measured, experts say that it is possible at the first appointment. With ultrasound conventional probe – at 5 weeks, vaginal – at 3-4.
Why do measurements of heartbeat
In early pregnancy the child’s heartbeat is virtually the only indicator that the fetus is carried out according to a predetermined algorithm without abnormalities and anomalies. Therefore the sooner a woman registers her pregnancy, the sooner the gynecologist can correlate the current norms of the baby’s heartbeat over the weeks with the actual situation of a particular woman. This will allow for early diagnosis of serious congenital defects, adjusting the lifestyle and habits of a pregnant woman, and, if necessary, prescribing the appropriate treatment. It is established that at the beginning of the 5th week, the heart rate is 80-85 beats per minute. Subsequently, compliance is as follows:
|Pregnancy term (weeks)
|Heart rate (beats/minute)
|Second-third trimester, before delivery
What abnormalities exist?
Knowing the normal rates of the baby’s heart rate according to the gestational age makes it easier for the doctor to start treating conditions that are indicated by deviations from the norm. They can be associated with both a sharp decrease and an increase in the frequency of contractions. Depending on this, the fetus is determined:
- bradycardia – deviation from the norm in the direction of reducing the child’s heart rate below 100 and especially – below 80 beats per minute, provided a non-monotonic rhythmic pulse can be corrected medically and is not life-threatening for the fetus;
- tachycardia – a steady heartbeat of 170-200 beats per 60 seconds, not life-threatening for the fetus, but may require early delivery if the situation worsens;
- monotonous heartbeat – the pulse varies depending on the activity and resting phases, may indicate fetal hypoxia and requires an ultrasound with Doppler ultrasound.
Causes of abnormal heart rate
In each case, when the infant’s heart rate is disturbed, there are a number of reasons for them. So with bradycardia, they may include:
- Rh conflict;
- multiple pregnancies.
- Bad habits, vitamin deficiencies, lack of fresh air;
- sedentary lifestyle;
- cord entanglement;
- chronic diseases of the heart and lungs of the mother;
- infectious diseases;
- high and low fluid volume;
- Taking certain medications;
- Dehydration due to prolonged toxemia;
- premature detachment of the placenta.
Causes that cause tachycardia of the baby’s heartbeat include:
- Dehydration caused by prolonged toxicosis;
- diseases of the endocrine system;
- maternal blood loss;
- Taking certain medications;
- Maternal heart and vascular disease;
- intrauterine infection.
There are also congenital cardiac abnormalities in the child, which are diagnosed with a concomitant developmental delay.
Congenital heart abnormalities
If the doctor notes a lag in the child’s heartbeat during abnormalities, this may be evidence of the development of a heart defect in the future baby. In this case, echocardiography or ultrasound of the little man’s heart is offered – this study is usually done in 18-28 weeks of pregnancy. It is worth undergoing.
Echo-CG including pregnant women from the “risk group”, who for various reasons have an increased likelihood of developing a heart defect in the fetus:
- If a malformation is suspected at the time of the fetal ultrasound;
- Over 40 years old;
- Those who have had infectious diseases during pregnancy;
- with congenital heart defects;
- who have already given birth to children with congenital heart defects.
Timely detection of possible abnormalities will allow choosing the appropriate method of delivery, as well as providing appropriate assistance to the baby immediately after birth.
Ways to measure heart rate – ultrasound
There are many proven techniques for listening to the heartbeat of a pregnant woman. They are made at different stages of pregnancy and can be made not only to determine the frequency and rhythm of the baby’s heartbeat, but also for other purposes that the doctor determines. These include, above all, the most popular and frequently used – ultrasound.
Ultrasound examination is performed from the first to the fifth month of pregnancy. In the early stages of the survey is carried out transvaginally – through the vagina, in a later period through the abdominal wall – transabdominally. During pregnancy is to make three ultrasound examinations. The first one is an ultrasound to determine the heartbeat, the second one is to look at the heart chambers to rule out malformations or other abnormalities, the third one allows us to find out the sex of the baby.
CTG (cardiotocography) and auscultation
To determine the baby’s heartbeat, cardiotocography is also used – recording and analyzing the work of the heart in different conditions – during movement, in its absence, under the action of various stimuli and uterine contractions. The method makes it possible to determine oxygen deficiency, when it is present, which is dangerous to reduce the adaptive capacity of the body, stunted development and growth and other pathologies.
Auscultation is used to listen to the heart tones with a stethoscope through the abdominal wall of the pregnant woman. The procedure is performed during visits to the gynecologist, as well as during delivery at 20-minute intervals to monitor the baby’s condition and determine the position of the fetus. Head presentation is diagnosed when the baby’s heartbeat is below the mother’s navel, transverse – when the heartbeat is flush with the navel, above the navel – evidence of pelvic presentation.
Ways to hear the fetal heartbeat yourself
To hear the pounding of the little heart is not necessary to wait for your next visit to the doctor. There are ways to listen to the baby’s heartbeat yourself with, for example, a stethoscope. The device is inexpensive, but you will need an assistant to listen. Also, it will not be easy to hear the heartbeat before the 25th week. It is important not to confuse the heartbeat with the baby’s movements and the mother’s peristalsis. Also use the fetal doppler – a fairly expensive portable device with headphones, which allows you to listen to the baby’s heartbeat as early as 8-12 weeks, it is undesirable to use it often and make the sessions longer than 10 minutes. It is possible to listen to the heartbeat by holding your ear up. The baby’s heartbeat becomes pronounced from the 30th week onwards. You can recognize them simply by listening to the belly of the mother-to-be.