Normal pulse rate in pregnant women in the first, second and third trimesters

If, during the period of bearing a child, a woman periodically notices an increased heart rate and discomfort, this is nothing more than tachycardia.

The normal rhythm of the heart is 60-90 beats per minute. With tachycardia this figure is exceeded. This is often observed during pregnancy - the woman’s body is overloaded, the cardiovascular system and all other organs work for two. In such a difficult and responsible period in life, it is important to carefully take care of your health. An increased heart rate is a warning sign.

Tachycardia during pregnancy is a pathology that can negatively affect not only the health of the expectant mother, but also interfere with the proper development of the baby in the womb. Therefore, when the first signs of palpitations appear, you should immediately consult a doctor.

What heart rate is considered normal at different times?

So are the standard heart rate limits (from 60 to 90 beats per minute) also required for the expectant mother?
After all, her heart pumps blood for two. Perhaps, in this case, not everything is so simple? Pregnancy (from 37 to 42 weeks) is divided into periods - trimesters, each of which includes 3 months. In the first, the formation of the main systems and organs of the unborn child occurs, in the second - their development and growth, and during the last, the mother’s body carries the formed fetus and prepares for childbirth. Since the tasks of the time periods differ, the requirements for the activity of the heart of the expectant mother also differ. So, let's look at the heart rate norms in pregnant women according to trimesters:

First trimester (until week 12, first ultrasound). Often, a woman finds out about pregnancy at the end of this period (unless the child is long-awaited and carefully planned, and there is scrupulous monitoring of the slightest changes in the reproductive system). Therefore, heart rate standards do not differ from the general population - from 60 to 90 beats per minute.
From the middle of pregnancy, the fetus and its container (placenta and membranes) gradually occupy an increasing part of the body of the expectant mother. This means that the uterus and its contents already require larger volumes of blood. To meet the demand of a growing body, the heart has to work harder. The frequency of impacts in 60 seconds increases by 10-15 from normal values. (If before pregnancy a woman’s pulse was 69-75 per minute, then after the fourth month they expect 75-90). The main thing is that the threshold of a hundred times in sixty seconds is not exceeded.
The third trimester is a crucial period. It is possible to develop preeclampsia (increased blood pressure, the appearance of protein in the urine and edema), a formidable harbinger of eclampsia (an attack of convulsions that threatens the life of the child and mother). That’s why monitoring your heart rate at this stage is so important. It is advisable not to exceed the threshold of 100 hits (15-20 higher than usual), but the critical level is 110.

Of course, you shouldn’t wait for the last number and assume that a reading of 114 beats for no apparent reason is a normal heart rate during pregnancy. Physical activity or experiences lead to an increase in heart rate. However, at rest, the heart rate quickly drops to 100 or below.

What is Down syndrome

Down syndrome is one of the most commonly diagnosed chromosomal pathologies. Anomalies of intrauterine development are caused by a spontaneous chromosomal mutation, in which one extra chromosome appears in 21 pairs.

Each cell of the human body consists of a nucleus and a membrane. Each nucleus contains genetic material that determines the appearance and function of both an individual cell and the entire organism. In humans, twenty-five thousand genes are assembled into twenty-three pairs of chromosomes. Each pair includes 2 chromosomes. In people diagnosed with Down syndrome, the twenty-first pair has an extra third chromosome, which causes characteristic external signs of the disorder in a person:

flat bridge of the nose;
narrow eye shape;
flat face and back of the head.

In addition to external characteristics, children with Down syndrome are characterized by mental retardation, have weak immunity, which is why they are highly susceptible to various infectious diseases.

Physiological features of heartbeat in a pregnant woman

Factors affecting the cardiovascular system during pregnancy:

Factor	Change	Significance
Circulating blood volume	Increasing. At week 36, the increase is 30-50% of the initial value, mainly due to plasma. During pregnancy with twins, the amount of fluid increases to a greater extent	Due to blood thinning, physiological anemia occurs (up to 100-120 g/l). But a decrease in viscosity has a beneficial effect on microcirculation, improving blood supply and nutrition to the fetus
Metabolism	Increases intensity	Providing the energy needs of two organisms at once
Length of the vascular bed	An additional uteroplacental circulation appears. If a woman is pregnant with fraternal twins, then there are two placentas at once, and the load on the heart will double	Nutrition of the unborn child, its growth and development
Pregnant body weight	Increases due to child weight gain and fluid retention in the body	The heart has to pump blood through a larger volume of tissue. It works harder
Uterus size	Increases	Restricted mobility of the diaphragm, increased intra-abdominal pressure
Heart position	Becomes horizontal	A functional murmur may occur in the fifth intercostal space along the left midclavicular line

All factors lead to such changes in the functioning of the heart:

Increased cardiac output (the amount of blood that enters the vascular bed during contraction of the left ventricle per minute) by 30-40% of normal at rest. In this case, the maximum value is reached at 20-24 weeks. Peculiarities:
subsequently, cardiac output increases the rise in heart rate (manifested by an increase in pulse).
Increase in minute blood volume due to the influence of hormones produced by the placenta:
progesterone.

Instrumental methods (echocardiography - ultrasound examination of morphological changes and electrocardiography) show the following features of the heart in pregnant women:

deviation of the electrical axis of the heart to the left (due to its displacement by the diaphragm that has risen as a result of the enlargement of the uterus);
enlargement of individual cardiomyocytes and the total mass of the heart;
change in contours similar to the mitral configuration (noticeable even on X-ray of the chest organs in a direct projection).

In the later stages, the condition of the fetus is determined by listening to the work of its own heart using an obstetric stethoscope (an instrumental method is also used - cardiotocography). The acceptable range is 110-170 beats per minute. If, during tachycardia or bradycardia in the mother’s body, the activity of the child’s cardiovascular system is not impaired, everything is in order.

Diagnosis of the first trimester

The first fetal ultrasound is performed between 11 and 14 weeks. In addition to an ultrasound examination, a woman must take a blood test for hCG. Only a comprehensive diagnosis will help conduct high-quality screening and exclude any developmental anomalies.

During an ultrasound, the doctor evaluates the following fetal indicators:

chorion structure;
coccyx-parietal length;
collar space thickness;
heart rate.

If the results of ultrasound screening do not correspond to generally accepted standards, the woman is prescribed a repeat, more in-depth diagnostic study.

How to identify the problem in time

Bradycardia leads to slight dizziness and even loss of consciousness. This type of arrhythmia includes a rate below 60 beats per minute. But if the expectant mother is an athlete and had a low heart rate before pregnancy, then there is nothing to worry about: in this case, this is a variant of the norm. Bradycardia is relatively rare.

Tachycardia is dangerous, even if it does not exceed the critical values described above, but is accompanied by the following symptoms:

deterioration of health;
weakness;
we cloud our consciousness;
nausea;
headache;
shortness of breath not caused by physical exertion.

Sometimes tachycardia is not associated with pregnancy and the accompanying changes in the body. And it occurs as a result of ARVI (acute viral infection), against the background of an increase in temperature (even low-grade fever has a dangerous effect on the child, especially immediately before birth) due to intoxication. In this case, they fight the virus, and not the change in heart rhythm. The pulse level should be understandable even in a pregnant woman. Do not attribute sudden changes in heart rate to hormonal changes in the body.

In order to identify a dangerous pathology in time, the described symptoms are correlated with a possible rhythm disturbance and a parallel is drawn between the clinical picture and the current pulse rate.

To control heart rate, you need to know the places where the arteries pass close to the skin (where they can be easily felt). It is advisable that there are solid bone elements nearby (by pressing the vessels against them, it is easier to catch the vibrations of the walls during the pulse wave).

Places for pulse examination:

Artery	Place of palpation	Methodology	Peculiarities
Radial	Groove between the styloid process of the bone of the same name and the tendon of the brachioradialis muscle	The index and middle fingers are placed on the palmar surface of the wrist of the other hand. Place of application: near the base of the first finger (thumb)	Palpation of the pulse on the radial artery is the standard for clinical examination of the patient
Sleepy	At the level of the upper edge of the larynx, at the site of bifurcation (bifurcation) of the common carotid artery	Place two fingers on the border of the upper and lower thirds of the neck, between the sternocleidomastoid muscle and the larynx (at the level of the Adam's apple)	If you strongly press the carotid artery on both sides, the carotid reflex is triggered, which leads to a sharp drop in heart rate and loss of consciousness

When it is too difficult to detect the pulsation of the arterial walls, heart rate is calculated based directly on the heart beats. To do this, find the left fifth intercostal space and at its intersection with a conventional perpendicular lowered from the middle of the collarbone, two fingers (middle and index) are placed on the same side of the body. At this point, the impulses of the apex of the heart are better felt.

Simplified algorithm: place your right hand under the base of the left breast, leaning slightly forward.

Because breasts are affected by hormones during pregnancy and their size increases, it is difficult to find the apex impulse. Therefore, preference is given to monitoring the pulse on the vessels.

If the peripheral artery was palpable before pregnancy (there are no congenital anomalies of its passage), and in the second half the pulse on it ceased to be palpable - this is an alarming sign. This situation is typical for severe swelling - one of the symptoms of gestosis (preeclampsia). It is necessary to tell the doctor about this and adhere to the recommendations prescribed by him (usually they do not include drug correction and at first are limited to diet changes).

Low heart rate

Some women, on the contrary, experience a decrease in heart rate during pregnancy, this is called bradycardia. Expectant mothers do not experience any unpleasant sensations when their heart rate drops, although some may experience dizziness and even fainting. Often, against the background of a low pulse, blood pressure also decreases significantly.

In general, bradycardia does not occur very often, but you still need to keep in mind that if you experience a decrease in heart rate, you need to consult a specialist, as this can lead to heart disease. It is worth saying that a slightly slow heart rate does not have a negative impact on both the condition of the pregnant woman and the development of the baby.

conclusions

The pulse rate in pregnant women in the third trimester differs most greatly from the average values in the population, exceeding them by 15-20 beats per minute. But this is a small price to pay for the coexistence of two organisms in one body. Such changes are physiological and explainable from a scientific point of view.

You should be concerned when your heart rate changes suddenly and for no apparent reason. If an expectant mother in the eighth month of pregnancy climbed the stairs on foot to the fifth floor, and at the same time her pulse jumped to 100 and dropped to 75 after a short rest, this is the norm. And if it’s up to 115, she has a headache, the patient is lying in bed, they go to the doctor.

Second trimester scan

A repeat ultrasound in the second trimester is performed before the 20th week. During screening, the doctor evaluates the following fetal parameters:

compliance of the development of internal organs and skeleton with current dates;
size and structure of internal organs.

In the second trimester, ultrasound clearly visualizes congenital heart defects, abnormalities in the structure of the bladder and brain. Also, 3 blood parameters are subject to analysis:

hCG;
alpha-fetoprotein;
free estyrol.

Decoding the results

Signs indicating that the fetus has chromosomal abnormalities:

The thickness of the collar space exceeds 2.8 mm. This indicates that the volume of fluid accumulating in the subcutaneous fold in the neck area exceeds normal values. On ultrasound, the fold appears white, and the fluid underneath appears darker.
Absence or small size of the nasal bone. This sign indicates Down syndrome.
Short upper jaw.
Heart rate exceeds permissible norms, heart defects.

Anomalies in the development of the musculoskeletal system, pathologies of internal organs, unformed ears - all these signs are characteristic of a chromosomal developmental abnormality.