What heart rate is considered normal at different times
So are the standard heart rate frames (from 60 to 90 beats per minute) obligatory for the expectant mother? After all, her heart pumps blood for two. Perhaps, in this case, not everything is so simple?
Pregnancy (37 to 42 weeks) is divided into periods - trimesters, each of which includes 3 months. In the first, the laying of the main systems and organs of the unborn child takes place, in the second, their development and growth, and during the latter, the mother's body bears the formed fetus and prepares for childbirth. Since the tasks of the time periods are different, the requirements for the activity of the heart of the expectant mother are also different. So, consider the pulse rates in pregnant women according to the trimesters:
- First trimester (up to 12 weeks, the 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 no scrupulous monitoring of the slightest changes in the reproductive system). Therefore, the heart rate standards do not differ from the general population - from 60 to 90 beats per minute.
- WITH mid 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 more blood volumes. To meet the demand of a growing organism, the heart has to work harder. The frequency of strikes in 60 seconds increases by 10-15 from the usual values. (If before pregnancy the woman's pulse was 69-75 per minute, then after the fourth month 75-90 is expected). The main thing is that the threshold is not exceeded a hundred times in sixty seconds.
- Third trimester - a crucial period. Possible development of preeclampsia (increased blood pressure, the appearance of protein in the urine and edema), a formidable harbinger of eclampsia (a seizure that threatens the life of the child and mother). Therefore, monitoring the heart rate at this stage is so important. It is advisable not to exceed the threshold of 100 hits (15-20 above the usual rate), but the critical level is 110.
Of course, you should not wait for the last figure and assume that an indicator of 114 beats for no apparent reason is a normal pulse during pregnancy. Physical activity or anxiety leads to an increase in heart rate. However, at rest, the heart rate quickly drops to 100 and below.
Physiological features of the heartbeat in a pregnant woman
Factors affecting the cardiovascular system during pregnancy:
| Factor | The change | Significance |
|---|---|---|
| Circulating blood volume | Increases. At the 36th week, 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 | Builds up the intensity | Providing the energy needs of two organisms at once |
| Length of the vascular bed | An additional uteroplacental circle of blood 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 |
| Body weight of a pregnant woman | Build up due to baby's weight gain and fluid retention | The heart has to pump blood through more tissue. It works harder |
| Uterus size | Is increasing | Limited mobility of the diaphragm, increased intra-abdominal pressure |
| Position of the heart | Becomes horizontal | Functional murmur may occur in the fifth intercostal space along the left midclavicular line |
All factors lead to such changes in the work of the heart:
- Increased cardiac output (the amount of blood that enters the vascular bed during the contraction of the left ventricle per minute) by 30-40% of the norm at rest. In this case, the maximum value is reached at 20-24 weeks. Peculiarities:
- in the first four to five months, cardiac output increases mainly due to an increase in the stroke volume (the amount of blood that leaves the left ventricular cavity during the next systole - contraction);
- further cardiac output increases the rise in heart rate (manifested by an increase in heart rate).
- An increase in the minute volume of blood due to the influence of hormones produced by the placenta:
- estrogen;
- 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 increase in the uterus);
- enlargement of individual cardiomyocytes and the total mass of the heart;
- a change in the contours of the type of mitral configuration (noticeable even by radiography of the chest cavity organs in direct projection).
In the later stages, the state of the fetus is determined by listening to the work of its own heart with the help of an obstetric stethoscope (they also use an instrumental method - cardiotocography). The allowed range is 110-170 beats per minute. If, with tachycardia or bradycardia in the mother's body, the activity of the child's cardiovascular system is not disturbed, everything is in order.
How to identify the problem in time
Bradycardia leads to mild dizziness and even loss of consciousness. This type of arrhythmia includes a frequency 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 in health;
- weakness;
- clouding consciousness;
- nausea;
- headache;
- shortness of breath, not due to 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 subfebrile condition dangerously affects the child, especially immediately before childbirth) due to intoxication. In this case, they fight the virus, and not the change in the heart rhythm. The heart rate should be explicable even in a pregnant woman. You should not write off the sharp jumps in heart rate for 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 desirable 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).
Pulse study sites:
| Artery | Palpation site | Methodology | Peculiarities |
|---|---|---|---|
| Beam | The 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 attachment - near the base of the first toe (thumb) | Pulse palpation on the radial artery is the standard of clinical research of the patient |
| Sleepy | At the level of the upper edge of the larynx, in the place of bifurcation (bifurcation) of the common carotid artery | Place two fingers on the border of the upper and lower third 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 walls of the arteries, the heart rate is considered, guided directly by the beats of the heart. To do this, find the left fifth intercostal space and at its intersection with the conditional perpendicular, lowered from the middle of the clavicle, two fingers are applied on the same side of the body (middle and index). At this point, the tremors of the apex of the heart are better felt.
Simplified algorithm: place the right hand under the base of the left breast, leaning slightly forward.
Since the breasts are exposed to hormones and increase in size during pregnancy, it is difficult to find the apex push. 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 felt, this is an alarming sign. This situation is typical for severe edema - one of the symptoms of preeclampsia (preeclampsia). It is necessary to tell the doctor about this and adhere to the recommendations prescribed by him (usually they do not include medical correction and at first are limited to dietary changes).
Conclusions
The pulse rate in pregnant women in the third trimester most strongly differs 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 scientifically explainable.
It is worth worrying when the heart rate has changed suddenly and for no apparent reason. If the expectant mother, in the eighth month of pregnancy, climbed the stairs on foot to the fifth floor, and at the same time the pulse jumped to 100 and dropped to 75 after a short rest, this is the norm. And if up to 115, she has a headache, the patient lies in bed - they turn to the doctor.
