Organs before and during pregnancy. Intrauterine development of the fetus by weeks. Endocrine glands during pregnancy

Basic knowledge of anatomy and physiology can help a woman avoid problems during conception, pregnancy and childbirth, as well as prevent various reproductive diseases. Therefore, it is useful to learn about such an important organ of the female reproductive system as the uterus: how it is arranged and how it changes during life, during the bearing and birth of a child.

What is the uterus and where is it located

The uterus is the organ of the female reproductive system in which the fetus develops from the moment the fertilized egg leaves the fallopian tube until the baby is born. It is shaped like an inverted pear.

The uterus is located in the small pelvis between the bladder and the rectum. Its position can change during the day: when the organs of the urinary and digestive systems are filled, it shifts slightly, and after urination or defecation, it returns to its original place. But the most noticeable change in the position of the uterus is observed simultaneously with its growth during pregnancy, as well as after childbirth.

The structure of the uterus

With the help of ultrasound of the uterus, you can see that it consists of three structural parts. The upper convex side is called the bottom, the middle expanded part is the body, and the lower narrow one is called.

The cervix consists of an isthmus, an elongated cervical canal and a vaginal part. Inside the uterus is hollow. Its cavity communicates on the lower side with the lumen of the vagina, and on the sides with the canals of the fallopian tubes.

The wall of the organ is three-layered:

1 The outermost layer facing the pelvic cavity is called perimetry. This membrane is closely connected with the outer integument of the bladder and intestines, and consists of connective tissue cells.

2 Middle, thickest layer - myometrium, includes three layers of muscle cells: outer longitudinal, circular and inner longitudinal - they are named so in the direction of the muscle fibers.

3 Inner shell, endometrium, consists of a basal and functional layer (facing the uterine cavity). Contains epithelial cells and many glands in which uterine secretions are formed.

In the cervix, there is more connective dense collagen tissue, and there are fewer muscle fibers than in other parts of the organ.

The wall of the uterus is permeated with numerous blood vessels. Arterial blood, saturated with oxygen, is brought by paired uterine arteries and internal branches of the iliac artery. They branch and give rise to smaller vessels that supply blood to the entire uterus and its appendages.

The blood that has passed through the capillaries of the organ is collected in larger vessels: uterine, ovarian and internal iliac veins. In addition to blood vessels, there are also lymph vessels in the uterus.

The vital activity of the tissues of the uterus is controlled by the hormones of the endocrine system, as well as the nervous system. Branches of the pelvic splanchnic nerves connected with the lower hypogastric nerve plexus enter the wall of the uterus.

Ligaments and muscles of the uterus

In order for the uterus to maintain its position, it is held in the pelvic cavity by connective tissue ligaments, of which the most famous are:

Interesting! Cervical cancer - a sentence?

1 Paired wide ligaments of the uterus(right and left) are attached to the membrane of the peritoneum. Anatomically, they are associated with ligaments that fix the position of the ovaries.

2 round ligament contains both connective tissue and muscle cells. It starts from the wall of the uterus, passes through the deep opening of the inguinal canal and connects with the fiber of the labia majora.

3 cardinal ligaments connect the lower part of the uterus (near the cervix) with the urogenital diaphragm. Such fixation protects the organ from displacement to the left or right side.

Through ligaments, the uterus is connected to the fallopian tubes and ovaries, which ensures the correct relative position of the organs of the female reproductive system.

In addition to the ligaments, the correct location of the pelvic organs, including the uterus, provides a set of muscles called the pelvic floor. The composition of its outer layer includes the ischiocavernosus, bulbous-spongy, superficial transverse and external muscles.

The middle layer is called the urogenital diaphragm and contains the compresses the urethra and the deep transverse muscle. The internal pelvic diaphragm combines the pubococcygeal, ischiococcygeal, and iliococcygeal muscles. The muscles of the pelvic floor prevent the deformation of organs, which would lead to a violation of their blood supply and performance of functions.

Uterine dimensions

When a girl is born, the length of her uterus is about 4 cm. It begins to increase from the age of 7. After the final formation of the reproductive system during puberty, the uterus reaches a size of 7-8 cm in length and 3-4 cm in width. The thickness of the walls in different parts of the organ and in different phases of the menstrual cycle varies from 2 to 4 cm. Its weight in a nulliparous woman is about 50 g.

The most significant changes in the size of the uterus occur during pregnancy, when in 9 months it increases to 38 cm in length and up to 26 cm in diameter. Weight increases to 1-2 kg.

After childbirth, the woman's uterus decreases, but no longer returns to its original parameters: now its weight is about 100 g, and its length is 1-2 cm more than before conception. Such dimensions persist throughout the childbearing period; after the second and subsequent births, there is no noticeable increase.

When the reproductive period of a woman's life ends and menopause occurs, the uterus decreases in size and mass, the wall becomes thinner, and the muscles and ligaments often weaken. Already 5 years after the end of menstruation, the body returns to the size that it was at birth.

uterus during pregnancy

During each menstrual cycle, a woman of reproductive age undergoes periodic changes in the structure of the uterus. Most of all they affect the functional endometrium.

At the beginning of the cycle, the woman's body prepares for a possible onset of pregnancy, so the endometrium thickens, more blood vessels appear in it. The amount of discharge from the uterus increases, which maintain the viability of spermatozoa.

If conception did not take place, after the death of the egg released from the follicle, the functional layer is gradually destroyed under the action of hormones, and during menstruation, its tissues are rejected and removed from the uterine cavity. With the beginning of a new cycle, the endometrium is restored.

If the egg is fertilized and pregnancy occurs, the continuous growth of the uterus begins. The thickness of the functional endometrium increases: it is no longer rejected, because menstruation has stopped. The layer is penetrated by an even greater number of capillaries and is supplied with more abundant blood to provide oxygen and nutrients to the organ itself (which is growing intensively) and to the baby developing in the uterine cavity.

Interesting! Can you get pregnant if you use a condom?

The volume of the myometrium also increases. Its spindle cells divide, elongate and increase in diameter. The layer reaches its maximum thickness (3-4 cm) around the middle of pregnancy, and closer to childbirth it stretches and becomes thinner because of this.

During regular examinations, starting from the 13-14th week of pregnancy, the gynecologist determines the height of the fundus of the uterus. By this time, its upper part, due to an increase in the size of the organ, extends beyond the small pelvis.

By week 24, the bottom of the uterus reaches the level of the navel, and at week 36 its height is maximum (palpable between the costal arches). Then, despite the further growth of the abdomen, the uterus begins to descend due to the baby moving down, closer to the birth canal.

The cervix during pregnancy is compacted and has a bluish tint. Its lumen is covered with a mucous plug, which protects the uterine cavity from infections and other adverse factors (read about the discharge of the plug on the website site). Due to the rapid growth of the uterus and displacement from its usual place, its ligaments are stretched. In this case, pain may occur, especially in the third trimester and with sudden movements.

Uterus contraction during pregnancy and childbirth

The myometrium (the middle, thickest layer of the uterus) contains smooth muscle cells. Their movements cannot be controlled consciously, the process of fiber contraction occurs under the influence of hormones (primarily oxytocin) and the autonomic nervous system. The muscle fibers of the myometrium contract during menstruation: this ensures the expulsion of secretions from the uterine cavity.

During the bearing of the baby, the uterus also sometimes contracts. Its surface hardens, and the pregnant woman may feel pain or heaviness in the abdomen.

This happens either because of a threat (hypertonicity), or during times that periodically occur when carrying a child and prepare the myometrium for labor.

Pregnancy is a state of continuous physical adaptation necessary to meet the needs of the growing fetus, as well as to ensure the constancy of the environment in which it occurs. The degree of this adaptation generally exceeds the needs of the fetus, so there are significant reserves to endure periods of stress or deprivation without significant changes in the environment of the fetus. Each of the systems of the mother's body is undergoing changes.

Endocrine system.

The endocrine system plays an extremely important role in the onset and development of pregnancy.

With the onset of pregnancy, changes appear in all endocrine glands.

In one of the ovaries, a new endocrine gland begins to function - the corpus luteum of pregnancy. It exists and functions in the body during the first 3-4 months. The corpus luteum hormone - progesterone - promotes the nidation of a fertilized ovum into the uterine mucosa, reduces its excitability and thereby favors the development of pregnancy. Progesterone has a protective effect on the fertilized egg and uterus. Under its influence, the transmission of nervous excitation from one muscle fiber to another slows down, as a result of which the activity of the neuromuscular apparatus of the uterus decreases. It promotes the growth of the uterus during pregnancy and the development of glandular breast tissue. The level of progesterone in the first weeks of pregnancy is 10 - 30 ng / ml, increasing from the 7th week of pregnancy above the above indicator.

The corpus luteum gradually regresses from 10 to 12 weeks of gestation, stopping its function completely by 16 weeks.

At this time, a new endocrine gland appears - the placenta, which connects the fetus with the mother's body. The placenta produces a number of hormones (gonadotropins, progesterone, estrogens, etc.). Chorionic gonadotropin contributes to the progression of pregnancy, affects the development of the adrenal glands and fetal gonads, and the processes of steroid metabolism in the placenta. Chorionic gonadotropin begins to be determined at the 3rd week of pregnancy, at 5 weeks its level in the urine is 2500 - 5000 IU / L, at 7 weeks it rises to 80,000 - 100,000 IU / L, and by 12 - 13 weeks the content of chorionic gonadotropin decreases to 10,000 - 20,000 IU / l and remains at this level until the end of pregnancy. The placenta produces placental lactogen, a chorionic somatotropic hormone, which, due to its anti-insulin action, enhances the processes of gluconeogenesis in the liver, reducing the body's tolerance to glucose, and enhances lipolysis.

The placenta also produces other hormones: melanocyte-stimulating hormone (MSH), adrenocorticotropic (ACTH) hormone, thyroid-stimulating hormone (TSH), oxytocin, vasopressin; as well as biologically active substances - relaxin, acetylcholine and others.

The placenta produces estrogen steroid hormones, one of which is estriol. Its level in the blood during pregnancy increases 5-10 times, and excretion in the urine increases hundreds of times. Estriol, neutralizing the action of other placental estrogens (estrone and estradiol), reduces the contractile activity of the uterus during pregnancy.

The pituitary, thyroid, and adrenal glands also undergo great changes.

So, one of the first indications of pregnancy may be the detection of a steady increase in luteinizing hormone (LH) from the pituitary gland. The production of melanocyte-stimulating hormone (MSH) usually also increases, which determines the tendency to hyperpigmentation in pregnant women. The anterior pituitary gland produces hormones that stimulate the function of the corpus luteum at the beginning of pregnancy. The posterior pituitary gland produces vasopressin and oxytocin. Oxytocin stimulates uterine muscle contractions, probably by facilitating the effects of prostaglandins. It is a weak antidiuretic and also has a vasodilating effect in isolation, although during pregnancy the latter is suppressed by estrogens. The accumulation and action of oxytocin are directly dependent on the content of estrogens and serotonin in the placenta, which block oxytocinase. This enzyme inactivates oxytocin in a woman's blood during pregnancy, it is produced in the trophoblast and is the enzyme of pregnancy.

In childbirth, the production of pituitrin by the posterior pituitary gland increases significantly. In the postpartum period, the hormones of the anterior pituitary gland contribute to the formation of a new function - the function of lactation.

In the first months of pregnancy, there may be some increase in thyroid function, in the second half - sometimes its hypofunction occurs. The level of circulating thyroxine during pregnancy generally does not increase, although the intensity of the main metabolism increases by 10% of the initial one. Clinically, pregnant women may show a slight swelling of the thyroid gland, due to an increase in its activity due to the need to compensate for the increased excretion of iodine by the kidneys.

During pregnancy, the fascicular zone of the adrenal cortex hypertrophies. The formation of glucocorticoids, which regulate carbohydrate and protein metabolism, is enhanced. In the adrenal cortex, the synthesis of cortisol, estrogens, progesterone and androgens increases. Under the influence of the activity of the adrenal glands, metabolic processes in the body of a pregnant woman increase, the content of cholesterol and other lipids in the blood increases, and skin pigmentation increases.

During normal pregnancy, aldosterone levels rise, which stimulates the excretion of sodium by the kidneys.

Insulin levels rise, probably due to stimulation of the islets of Langerhans by placental lactogenic hormone.

the cardiovascular system.

During pregnancy, the cardiovascular system of healthy women undergoes significant changes.

hemodynamic changes.

Hemodynamic changes during pregnancy are a manifestation of compensatory-adaptive adaptation to the coexistence of mother and fetus organisms. They are expressed in an increase in cardiac output, an increase in blood volume, an increase in heart rate and venous pressure. Changes in hemodynamics are closely related to an increase in body weight, uterus, fetus, placenta, an increase in metabolic rate by 15-20%, and the inclusion of additional placental circulation. One of the main mechanisms that ensure the maintenance of optimal microcirculation conditions in the placenta and vital organs of the mother (heart, brain, kidneys) during pregnancy and childbirth is the physiological hypervolemia of pregnant women. The volume of blood plasma in pregnant women begins to increase from the 10th week of pregnancy. An intensive increase in the volume of circulating blood plasma continues until the 34th week of pregnancy, after which the increase continues, but much more slowly. At the 34th week of pregnancy, an increase in the amount of blood plasma reaches 30-40%, by the end of pregnancy - 50%. Thus, the VCP by the end of pregnancy is 3900 - 4000 ml. The volume of erythrocytes also increases, but to a lesser extent, increasing by the end of pregnancy by about 18 - 20% of the initial level. The disproportion between the volume of plasma and the volume of blood cells leads to the fact that at 26-32 weeks of pregnancy, the hemoglobin content and the number of red blood cells, despite their absolute increase, can decrease by 10-20%, i.e. oligecythemic anemia develops and blood viscosity decreases. Thus, in almost every woman during pregnancy, there is a relative decrease in hemoglobin levels, sometimes called "pregnancy hydremia", which can be prevented by the appointment of iron supplements. This state of the so-called physiological hypervolemia(autohemodilution).

Physiological hypervolemia is an important compensatory-adaptive mechanism, which: 1). maintains optimal microcirculation conditions in vital organs during pregnancy; 2). allows some pregnant women to lose 30 - 35% of blood volume without the development of severe hypotension (the protective effect of autohemodilution).

During pregnancy mean arterial pressure rises from 95 mm Hg. normally up to 105 mm Hg, which facilitates the transfer of oxygen from the mother to the fetus. The average blood pressure is determined by the formula: blood pressure cf. \u003d (SBP + 2DAD) / 3,

where SBP is systolic blood pressure and DBP is diastolic blood pressure.

Cardiac output, which is 4.2 l / min in a healthy non-pregnant woman, increases at 8-10 weeks to approximately 6.5 l / min, and this level is maintained almost until the very birth, immediately before which there is a tendency to reduce the emission. The increase in output is made up of an increase in stroke volume and an increase in heart rate from 72 to 78.

Cardiac minute volume (MOV) with a physiologically proceeding pregnancy, it increases by an average of 30-32% by 26-32 weeks of pregnancy. By the end of pregnancy, MOS decreases slightly, and at the beginning of labor it increases and slightly exceeds the initial value.

Peripheral vascular resistance decreases especially towards the middle of pregnancy, therefore, between the 16th and 28th week, there is a tendency for a decrease in blood pressure. The decrease in total and peripheral vascular resistance is explained by the formation of the uteroplacental circulation and the vasodilating effect of progesterone and estrogens. There is vasodilation of the skin, as a result of which the woman feels less cold and can sometimes feel worse in warm weather. An increase in the blood flow surface is noticeable on the ulnar side of the palms in the form of palmar erythema. Some women have petechial hemorrhages in the area of ​​palmar erythema. They are not considered a manifestation of damage to the liver or the hemostasis system, but are only a clinical manifestation of an increase in the concentration of estrogen and disappear 5 to 6 weeks after birth.

Blood pressure, apart from the tendency to a slight drop in the middle of pregnancy, it practically does not change in a healthy pregnant woman. The individual level of blood pressure is determined by the ratio of 4 factors:

1) a decrease in total peripheral resistance;

2) a decrease in blood viscosity;

3). an increase in the volume of circulating blood (BCC);

4).an increase in cardiac output.

The first two factors contribute to a decrease in blood pressure, the last two - to an increase. The interaction of all four factors maintains blood pressure at an optimal level.

Heart activity.

During pregnancy, physiological tachycardia is observed. In the III trimester of pregnancy, the heart rate (HR) is 15-20 beats / min higher than the heart rate before pregnancy. Central venous pressure rises to an average of 8 cm of water. (outside of pregnancy is 2-5 cm of water). The pressure in the veins of the upper extremities does not change. The pressure in the veins of the lower extremities increases. This is partly due to gravity and partly due to obstruction caused by the return of blood from the uterus and placenta. The pregnant uterus compresses the inferior vena cava. Deterioration of venous outflow through the lumbar and paravertebral veins, as well as a decrease in cardiac output in some women causes collapse. Therefore, pregnant women are advised to avoid the supine position.

The high standing of the fundus of the uterus leads to a limitation of the mobility of the diaphragm and a change in the position of the heart in the chest. In this regard, in half of healthy women during pregnancy, a systolic murmur is heard at the apex of the heart. There is an increase in the I tone at the apex of the heart, sometimes there is an emphasis on the pulmonary artery. There are no significant ECG changes during pregnancy.

Hematological parameters during pregnancy.

Table 3

Normal hematological parameters of pregnancy

The total number of leukocytes increases from 7,500 to 10,000 in 1 mm 3, and the erythrocyte sedimentation rate reaches a maximum of 50 mm in the first hour.

The number of platelets approximately doubles, reaching 316,000 in 1 mm 3 by the time of delivery. The content of serum fibrinogen increases from 3 g/l before pregnancy to 6 by the time of delivery. In the II and III trimesters of pregnancy, the content of blood coagulation factors increases, the prothrombin index increases. The rate of blood coagulation gradually increases, the structural properties of the blood clot increase.

The level of proteins in the blood plasma decreases from 70 to 60 g / l, which causes a drop in the osmotic pressure of the plasma, due to which there is a tendency to edema. The albumin/globulin ratio drops from 1.5 to 1. These changes occur due to a decrease in the level of albumin and an increase in the content of alpha and beta globulins. The level of gamma globulins also decreases.

respiratory system.

Pregnancy requires an increase in respiratory exchange to meet the increasing metabolic demands due to the presence of the fetus - a continuously growing organism with intensive metabolic processes, as well as an increase in maternal metabolism. In this regard, starting from 8-9 weeks of pregnancy, the mother's respiratory system undergoes a number of morphological and functional adaptive changes, which, together with changes in the blood and circulatory systems, provide oxygen supply and carbon dioxide release in accordance with the needs of the body.

Morphofunctional changes in the chest.

By the end of pregnancy, the diaphragm rises by 4 cm, and, despite this, its excursions during breathing have a large scope, both in a vertical and horizontal position. High mobility of the diaphragm is provided by a decrease in the tone of the abdominal muscles and expansion of the chest, the circumference of which increases by 6 cm due to an increase in the transverse diameter. Changes in the chest and diaphragm lead to a change in the type of breathing in pregnant women, which becomes predominantly diaphragmatic.

Ventilation of the lungs.

During pregnancy, lung activity increases due to increased oxygen demand. The total oxygen consumption by the end of pregnancy increases by 30 - 40%, and during attempts - by 150 - 250% of the original, reaching 800 - 900 ml O 2 / min in primiparas.

P CO2 drops from 38 to 32 mm Hg. due to hyperventilation, which facilitates the removal of CO 2 into the maternal bloodstream.

These compensatory reactions are provided by the processes of hyperventilation of the lungs, hyperfunction of the heart, activation of erythropoiesis, leading to an increase in the number of circulating red blood cells.

However, diaphragmatic excursion during pregnancy remains limited and pulmonary ventilation difficult. This is mainly expressed in increased breathing (by 10% of the original), and a gradual increase (by the end of pregnancy - and 30-40% of the original) respiratory volume. Minute respiratory volume (MOD) increases from 8.4 l/min at 12 weeks of gestation to 11.1 l/min by term.

The increase in tidal volume occurs due to a decrease in the reserve output volume.

Vital capacity of the lungs(maximum volume of air removed by maximum expiration after maximum inspiration) does not actually change during pregnancy. Despite the fact that vital capacity does not undergo significant changes during pregnancy, its components - the current volume and inspiratory reserve volume - undergo large quantitative changes. The current volume - the amount of air inhaled and exhaled during normal breathing - progressively increases from the third month to the term of delivery, reaching values ​​​​of about 100 - 200 ml (40%) more than in non-pregnant women. The inspiratory reserve volume increases in late pregnancy due to an increase in the size of the chest. The reserve tidal volume combined with the current volume is inspiratory capacity, which in the sixth to seventh months of pregnancy is about 120 ml (5%) more than the rate of non-pregnant women. In contrast, expiratory reserve volume decreases by about 100 ml (15%) in the second half of pregnancy, reaching its lowest values ​​at 24–28 weeks of gestation. The decrease in the expiratory reserve volume is explained by the increase in the current volume, and since the vital capacity does not change, by the end of a normal inspiration, the compression atelectasis of the lungs of a pregnant woman increases and they contain relatively less air than the lungs of a non-pregnant woman.

Residual volume - the amount of air remaining in the lungs after maximum exhalation is about 20% less during a full-term pregnancy than outside it. In the same time functional residual lung capacity(FOE) and total lung volume(OOL) due to the high standing of the diaphragm are reduced. Maximum lung capacity- the volume of air contained in the lungs by the end of the maximum breath - is reduced.

The work of the respiratory muscles increases, their oxygen consumption increases, although the resistance of the respiratory tract decreases by almost 1.5 times by the end of pregnancy.

Arterial partial pressure of oxygen during a normal pregnancy decreases to 30 - 32 mm Hg, however, due to the simultaneous increase in the excretion of sodium bicarbonate by the kidneys pH blood remains normal.

Mechanical properties of the lungs. During pregnancy, the overall resistance of the lungs is less by 50% than outside pregnancy due to the weakening of the tone of the smooth muscles of the bronchioles due to excess progesterone.

Lung perfusion increases during pregnancy, oxygen diffusion through the alveolar-capillary membrane does not change, or decreases slightly, while maintaining the ability to increase during exercise.

Thus, morphofunctional changes in the respiratory system during pregnancy create the necessary conditions for the implementation of pulmonary hyperventilation, which, combined with an increase in pulmonary perfusion and an increase in the exchange alveolar-capillary area, makes it possible to increase respiratory gas exchange in accordance with the needs of the body of the pregnant woman and her growing fetus.

urinary system.

In the first and second trimester of pregnancy, renal blood flow increases, gradually returning to its original level by the time of delivery. In late pregnancy, an enlarged uterus prevents venous drainage from the kidney, although this is only detected when the pregnant woman lies on her appropriate side.

The intensity of glomerular filtration increases by 50%, returning to normal only after childbirth. Inulin clearance increases from 90 to 150 ml/min. In addition, almost 100 liters of liquid are filtered daily. Despite this, urine output is somewhat reduced. During the second trimester of pregnancy, there is an increase in cardiac output, plasma volume, and glomerular filtration rate up to 40%. In the III trimester of pregnancy, these indicators return to their original level. In the last 3 months of pregnancy, renal blood flow is 10% higher than normal, while glomerular filtration returns to normal by the end of the eighth month of pregnancy.

Due to increased glomerular filtration and increased plasma volume, serum creatinine levels are lower than in non-pregnant women. This is also facilitated by a decrease in protein catabolism during pregnancy.

The excretion of urea and uric acid also increases. Around 16-20 weeks of gestation, the renal threshold for glucose falls sharply, which is why glucosuria is quite common. Excretion of 140 mg/day of glucose in the urine is considered the upper limit of physiological glucosuria.

During pregnancy, about 20% of women experience orthostatic proteinuria. The probable cause of this proteinuria may be compression of the inferior vena cava by the liver and the uterus of the veins of the kidneys. The main indicators of kidney function are presented in table 4.

Under the influence of progesterone, the muscle fibers of the bladder hypertrophy, due to which it becomes elongated and sluggish, which can lead to its bending and stagnation of urine. Due to the relaxing effect of progesterone on smooth muscle muscles, some atony of the ureters is observed, which can contribute to reverse reflux and urine reflux into the overlying parts of the urinary system. The situation is aggravated with the growth of the uterus, which presses down on the bladder, which together contributes to the introduction of infection, the development of hydronephrosis. Thus, conditions are created for the development of pyelonephritis during pregnancy, the risk of which is especially high in violation of the ecology of the vagina.

Table 4

Kidney function during pregnancy.

sexual organs.

In the reproductive system, the main changes concern the uterus. By the time of delivery, the uterus increases to a size of 28x24x20 cm. Thus, the length of the non-pregnant uterus is 7-8 cm, by the end of pregnancy it increases to 37-38 cm. The transverse size of the uterus increases from 4-5 cm outside of pregnancy to 25-26 cm. the mass of the uterus increases from 50-100 g outside of pregnancy to 1000-1500 g by the time of delivery.

During this period, it shifts the diaphragm upward, and in the supine position it compresses the inferior vena cava so much that it interferes with venous flow to the heart from the lower half of the body and causes hypotensive syndrome. The increase in the size of the uterus is determined rather by hypertrophy of muscle fibers than by an increase in their number. Each muscle fiber lengthens 10-12 times and thickens 4-5 times. Hypertrophy occurs under the influence of estrogens and progesterone.

The lower segment of the uterus begins to form at about 12 weeks of gestation, partly from the lower part of the uterine body and partly from the upper part of the cervix, which is lined with a glandular epithelium similar to that of the body of the uterus, while the cervical canal is slightly shortened. The cervix becomes softer and vascularized, taking on a bluish tint. The cervical canal remains tightly closed with a plug of viscous, opaque mucus that acts as a barrier to bacteria from entering the vagina. The epithelium of the cervical canal grows, the glandular tissue becomes more active.

Softens and becomes more plastic and elastic and the muscular tissue of the body of the uterus. The uterus acquires the ability to respond with an increase in tone in response to various irritations. The mucous membrane of the uterus undergoes a certain restructuring, a decidual (falling away) membrane develops from the functional layer of the endometrium.

The vascular network of the uterus grows: expand, lengthen, increase in the number of arterial, venous, lymphatic vessels. Blood vessels in the area of ​​​​attachment of the placenta grow especially. The number of nerve elements of the uterus increases, new sensitive receptors are formed that ensure the transmission of nerve impulses.

The excitability of the uterus in the first months of pregnancy decreases. Gradually, however, the normal rhythmic contractions of the uterus, characteristic of the luteal stage of the menstrual cycle, increase, although they remain completely painless (Brexton Hicks contractions). As the pregnancy progresses, these contractions gradually increase in strength and frequency, and although they are not strong enough to cause the cervix to dilate, they may have something to do with the "ripening" of the cervix.

In the muscle of the uterus, the amount of the contractile protein actomyosin progressively increases, the level of total phosphorus increases, and creatine phosphate and glycogen also accumulate. Biologically active substances gradually accumulate: serotonin, catecholamines, histamine. The ligaments of the uterus lengthen and thicken, which helps to keep the uterus in the correct position both during pregnancy and childbirth. Round uterine ligaments, sacro-uterine ligaments are exposed to the greatest hypertrophy.

The fallopian tubes thicken due to serous impregnation of the tissues. As pregnancy progresses, the fallopian tubes descend along the lateral surfaces of the uterus, the tubes become inactive during pregnancy.

The ovaries, as the corpus luteum degenerates, become inactive, cyclic changes in them stop, with the growth of pregnancy, they move from the pelvic cavity to the abdominal cavity.

The vagina and pelvic floor become softer, the number of vessels in them increases. The thickness of the vaginal epithelium also increases, the reaction of the vaginal environment becomes more acidic.

The blood supply to the external genital organs increases, varicose veins may appear on the labia majora. The elasticity and suppleness of the walls of the vagina, external genital organs and the pelvic floor increases, as a result of which they become more extensible, preparing for the passage of the fetus during childbirth.

Gastrointestinal tract.

As pregnancy progresses, some displacements of the digestive organs in the anatomical sense occur. Thus, the stomach is located more horizontally, and increased pressure on the diaphragm can lead to disruption of the activity of the sphincters of the stomach, due to which its acidic contents burp and cause heartburn. The small intestine moves upward and toward the wall of the peritoneum. The caecum with the process moves up and to the side - a trap for the careless surgeon.

The contractility of the smooth muscles of the intestine decreases, probably under the influence of progesterone, which often leads to constipation. The tendency to constipation may be exacerbated by increased absorption of water in the colon. Often bile stasis is formed, which leads to cholestatic jaundice. The acidity of the gastric juice decreases.

Pregnancy during its normal course usually does not cause any significant changes in the liver. Histologically, an increase in the content of glycogen and fatty deposits in the liver cells were revealed. Characteristic of pregnancy is an increase in alkaline phosphatase (from 26 to 75 IU versus 25 IU in non-pregnant women), direct bilirubin (up to 0.5 - 3.0 mmol / l).

musculoskeletal system.

The relaxing effect of progesterone during pregnancy also affects the ligaments and joints, it is especially pronounced on the joints of the pelvis, which facilitates the passage of the fetus through the birth canal. This phenomenon is partly due to the flattening and stretching of the feet in pregnant women. Skeletal muscle tone is slightly reduced, which can lead to drooping of the shoulder girdle and compression of the brachial plexus, causing typical ulnar paresthesia. However, this rarely happens. A more common manifestation during pregnancy is the development of lumbar lordosis due to the need to balance the weight of the enlarged uterus. This lordosis can increase back pain. Lordosis is aggravated if a woman walks in high-heeled shoes.

Leather.

In pregnant women, skin pigmentation increases, especially pronounced on the face, around the nipples and the white line of the abdomen, especially pronounced in brunettes (chloasma uterinum). . This phenomenon is due to an increase in the amount of circulating melanostimulating hormone. Longitudinal stripes 5-6 cm long and about 0.5 cm wide appear on the abdomen and thighs. At first they are pink, but then they become pale and more compacted. They are thought to be caused by separation of the elastic layer of the skin from other layers due to increased levels of circulating adrenal hormones. They are called pregnancy stripes (striae gravidarum). Sometimes there are birthmarks.

Increases the intensity of the sebaceous and sweat glands.

Nervous system

From the moment of the onset of pregnancy, the flow of impulses begins to flow into the mother's central nervous system, which causes the development of a local focus of increased excitability in the central nervous system - a gestational dominant. The excitability of the cerebral cortex is reduced up to 3-4 months of pregnancy, and then gradually increases. The excitability of the underlying parts of the central nervous system and the reflex apparatus of the uterus is reduced, which ensures the relaxation of the uterus and the normal course of pregnancy. Before childbirth, the excitability of the spinal cord and the nervous elements of the uterus increases, creating favorable conditions for the onset of labor. The tone of the autonomic nervous system changes, in connection with which pregnant women often experience drowsiness, tearfulness, irritability, sometimes dizziness and other disorders. Usually these phenomena gradually disappear with the growth of pregnancy.

Metabolism.

During pregnancy, basal metabolic rate and oxygen consumption increase. The basal metabolic rate for a healthy non-pregnant woman is approximately 2300 calories per day. During pregnancy, the basal metabolic rate increases by about 10%, due to increased oxygen consumption and fetal activity, so that the total energy expenditure is approximately 2500 cal per day. In total, additional energy expenditure for the entire pregnancy is approximately 68,000 calories, half of which is covered by fat and one third by carbohydrates. Proteins provide only 6.5% of energy, as they are used almost exclusively for tissue formation.

In the body of a woman, protein substances are accumulated that are necessary to meet the needs of a growing fetus in amino acids.

Changes in carbohydrate metabolism lead to the accumulation of glycogen in the cells of the liver, muscles, uterus, placenta. Carbohydrates pass to the fetus in the form of glucose, which provides the energy needs of the fetus, the processes of anaerobic glycolysis.

In the blood of pregnant women, the concentration of neutral fat, cholesterol and lipids increases. Fats pass to the fetus in the form of glycerol and fatty acids, which are used as an energy material, as well as for building tissues.

During pregnancy, the needs of the pregnant woman's body for calcium, phosphorus, and iron salts increase, which are necessary for the ossification of the fetal skeleton, the formation of its hematopoiesis, and the development of the nervous system.

The total weight gain during pregnancy is normally 12 kg. One third of the increase, 4 kg, is gained in the first half of pregnancy, and the remaining two thirds, 8 kg, in the second. 60% of total body weight gain is due to water retention caused by sodium accumulation. Retained water is distributed as follows: in plasma 1.3 l, in the fetus, placenta and amniotic fluid 2 l, in the uterus, mammary glands 0.7 l, and in extragenital interstitial fluid 2.5 l. By the time of delivery, the fetus and amniotic fluid together weigh about 5.5 kg, and this mass is lost after childbirth. The remaining 6.5 kg fall on the share of the uterus, mammary glands, fat reserves (especially on the hips and buttocks).

After a sharp decrease in body weight in the first four days after birth due to increased urine output resulting from the cessation of placental hormones, it continues to gradually decrease over the next 3 months or so.

Tests for self-control .

The volume of circulating blood during pregnancy increases by:

Doesn't change at all.

2. Physiological hypervolemia of pregnant women occurs at the time:

20-22 weeks pregnant

- *34-35 weeks of pregnancy

38-39 weeks pregnant

16-15 weeks of pregnancy.

3. The level of proteins in the blood plasma during pregnancy decreases to:

4. Total oxygen consumption by the end of pregnancy:

- *increases

Decreases

5. Normally during pregnancy it is noted:

- *acceleration of breathing

Decreased breath

The respiratory rate does not change.

6. Physiological glucosuria during pregnancy is spoken of at the level of glucose in the urine:

120 mg/day

130 mg/day

- *140 mg/day

150 mg/day

7. The corpus luteum of pregnancy functions in the body until:

2 months pregnant

3 months pregnant

- *up to 3-4 months of pregnancy

Until the due date.

8. The placenta secretes all of the following except:

Chorionic gonadotropin

Placental lactogen

melanocyte-stimulating hormone

* placental insulin.

9. Formation of glucocorticoids during pregnancy:

- *intensifies

Decreases

Does not change significantly.

10. The total weight gain during pregnancy is normally:

11. The main function of chorionic gonadotropin is:

- * maintaining the function of the corpus luteum

Initiation of implantation

Initiation of breast development

Determination of fetal viability.

The process of bearing and giving birth to a child is a normal physiological phenomenon for any woman: since ancient times, nature has provided everything to fulfill this higher destiny of a woman. And everything in the complex mechanism of the female body is arranged in such a way as to ensure its normal functioning at a time when a little man is growing in it. In this regard, after the conception of a child is inevitable, the body adapts to a new state, and its main task now is to preserve the fetus and ensure its normal development. That is why any pregnant woman already from the first months feels the "restructuring" of the organs, which before pregnancy worked in a completely different mode. This condition is considered normal, if not accompanied by any pathological conditions.

First of all, after the "settlement" in the body of a woman of a baby, the genitals of a pregnant woman undergo significant changes. The uterus, in which the fetus gradually grows, increases tenfold as it develops. So, if before the onset of pregnancy, the weight of the uterus averaged about 50 grams, by the end of pregnancy this figure can reach 1 thousand grams or more. In parallel, the volume of the uterine cavity also increases: by the time of delivery, its volume can be 520-550 times greater than before fertilization. The number of muscle fibers in the uterus also increases, the uterine ligaments lengthen, which ensures the normal development of the fetus. The ovaries also change in size, increasing in size. In addition, one of them contains the "yellow body" - here special hormones are produced that ensure the normal course of pregnancy. The mucous membrane of the vagina, meanwhile, loosens, the walls of the vagina become more elastic - just like the external genitalia (small and large). The loosening of tissues in the future will contribute to an easier passage through the birth canal of the baby, and therefore all these changes are extremely important in physiological terms.

As the genital organs change, significant changes are observed in the organs of digestion and urination. Many pregnant women are familiar with cardinal changes in taste preferences - in addition to increased appetite, they are also expressed in cravings for salty or sour foods, cravings for unusual substances (chalk, soap, clay), perversion of olfactory sensations. This situation is explained by a change in the tone of the vagus nerve, which regulates the work of many internal organs. As for the digestive organs: the growing uterus greatly affects the state of the intestine - under the pressure of the uterus, it shifts up and to the sides, the intestinal tone decreases. Such a shift, coupled with fetal pressure, causes frequent. The stomach, in turn, reacts to squeezing by the growing uterus with heartburn. the prevention of such an unpleasant phenomenon should be the regular use of mineral water, as well as the rejection of a late dinner. The growing uterus presses on the bladder, which leads to increased urination. A big load during pregnancy lies on: this natural filter provides purification from decay products not only of the body of the expectant mother, but also the neutralization of toxins that can harm the baby. The location of the liver also changes - it is pushed up by the uterus and takes a lateral position. In this condition, the outflow of bile is often difficult, which can contribute to the appearance of hepatic colic. Just like the liver, the kidneys also work with double tension.

A significant load is provided to the cardiovascular system of the pregnant woman. Since the growing fetus needs to be provided with enough oxygen and nutrients, the heart has to work harder. In addition, the volume of circulating blood also increases, a new circle of blood circulation appears in the body - placental. All this entails an increase in the mass of the muscles of the heart, their rapid contraction. It is this fact that causes a rapid pulse during pregnancy - in the second half of pregnancy, the speed of heart beats reaches 75-90 beats per minute. In parallel, changes in blood pressure indicators can be observed: in the first half of pregnancy, it can be, and in the second half, it can rise slightly. The pressure of a pregnant woman will have to be carefully monitored: a significant increase or decrease in it may indicate the onset of any complications of pregnancy.

Pregnancy also brings changes to the functioning of the respiratory system. Since the body needs to be supplied with enough oxygen, and the enlarged uterus, meanwhile, restricts the movement of the diaphragm, the lungs have to work harder. Thus, the frequency of breathing increases, it becomes deeper. The volume of the lungs, on the contrary, even increases somewhat, the tissue becomes more juicy, the bronchial mucosa swells. In the last months of pregnancy, due to changes in the respiratory organs, as well as difficulties in gas exchange, the risk of inflammatory diseases of the respiratory tract increases significantly. In order to avoid such situations, experts advise pregnant women, when carrying a baby, to resort to various breathing techniques that help to saturate the body with oxygen in sufficient quantities.

It should be noted that changes in the organs of a woman during pregnancy are considered a normal physiological phenomenon. Due to the fact that the body is able to change the rhythm of work, adapting to new conditions of functioning, the planned development and formation of the fetus is ensured. The restructuring of organs during the bearing of a baby is a temporary phenomenon, in most cases disappearing after the baby is born.

Specially for- Tatyana Argamakova

Pregnancy is undoubtedly the most emotional and unforgettable period in the life of any woman. Expecting a child changes not only the perception of the expectant mother, but also her. The female body is being transformed to help new life emerge.

Internal organs during early pregnancy

What is the location of the internal organs during pregnancy by week? Already in the first days after the onset of conception, changes occur in the female body, often imperceptible to the woman herself. And with the course of pregnancy, almost all internal organs change in size and function in a new way. Some of them even move from their usual places under the pressure of the growing fetus.

First of all, the hormonal background changes, progesterone, the hormone responsible for strengthening the uterine mucosa, begins to be actively produced. Thanks to this, the fetus receives a normal blood supply. Progesterone helps the body fight external infections. At the same time, a large amount of this hormone provokes digestive disorders and can become a catalyst for toxicosis in the early stages.

Important transformations also take place in the genitals of a woman. At the very beginning of pregnancy, the color and structure of the cervix change. The mucous membranes gradually loosen, the walls of the uterus become elastic. This helps it grow as the fetus grows. Before conception, the weight of the uterus is 20-25 grams, and already before the very birth, it can reach a kilogram or more. At 4-5 weeks of gestation, the uterus reaches the size of a chicken egg, by about the fourth month it already goes beyond the pelvis, and closer to childbirth it will increase so much that it reaches the ribs. Its mass, size and volume increase tenfold. During the bearing of a child, the number of blood vessels supplying the uterus also increases. The ligaments that hold it in the pelvis become elastic during pregnancy and gradually stretch. A woman can feel this process with slight pulling pains on the sides of the abdomen.

The ovaries also become larger compared to their previous size, one of them contains the corpus luteum, which produces special hormones for the normal course of pregnancy.

From the very beginning of pregnancy, changes also occur in the female breast. The glands are preparing for the upcoming lactation (the production of breast milk). The chest begins to increase, the nipples become rough.

Pregnancy changes the state of the so-called vagus nerve, which affects the functioning of some internal organs. For this reason, pregnant women often increase their appetite, taste preferences change, previously incompatible products seem tasty: a sandwich with sausage and jam, cakes with tomato juice. Sometimes a woman feels nauseous. As a rule, these phenomena disappear by the end of 12-14 weeks.

While waiting for a child, a woman's body weight increases by 10-12 kilograms, although it happens that for the entire period the expectant mother gains more than 20-25 kilos. Usually in the first half of pregnancy, weight gain is insignificant - 4-5 kilograms. The main increase in body weight occurs in the second half of the term.

Some women already at the beginning feel changes in the urinary system. I want to go to the toilet more often. Such changes are caused by the pressure of an ever-growing uterus on the bladder and an increase in the level of the hormone progesterone in the blood. The latter has a relaxing effect on the muscles of the sphincter of the bladder.

The main transformations of the internal organs occur in the second half of gestation as the fetus and the uterus in which it is located grow. How do organs move during late pregnancy?

For nine months, the amount of circulating blood in the female body increases, a new circulatory system is formed - the placental one. The heart works with an additional load, the mass of the heart muscle increases. In the later stages, the heart rate increases (up to 90 beats per minute). Quite often, pregnancy also affects the state of blood pressure. In the first weeks, it may be below normal, and in the later stages it may increase. The level of pressure must be monitored, because its high rates, especially at the end of pregnancy, can signal pathological processes. For example, about the development of preeclampsia (late toxicosis).

Expecting a baby affects the condition of the lungs. They are also working hard. After all, on the one hand, the need for oxygen increases, they need to be provided not only for the mother, but also for the growing fetus. On the other hand, the growing uterus begins to press on the diaphragm. The mucous membrane of the bronchi swells. The woman breathes faster and deeper. Often, pregnant women are recommended special breathing exercises (without holding their breath) to prevent possible inflammation of the respiratory tract. Regular walks in the fresh air are also suitable for this. Before childbirth, the situation is a little easier, the pressure on the diaphragm decreases, because the fetus descends to the birth canal.

Almost more than all other internal organs, the stomach suffers, especially in recent months. He moves up. The growing uterus constantly presses on it, because of this, gastric juice enters the esophagus - and heartburn occurs.

During pregnancy, the location and intestines change. At first, it rises, and at the end of pregnancy it moves apart, giving way to the uterus with the fetus, which descends to the birth canal. Often such bowel movements provoke constipation. To avoid them, a pregnant woman should drink enough water, eat small meals, include fiber-rich foods in the menu and have enough gentle physical activity.

The main filter of the body - the liver, which during pregnancy works with a double load, also shifts up and to the side. Sometimes this can lead to problems with the outflow of bile and the appearance of colic. In such cases, doctors recommend a special diet.

Although the kidneys do not move, they also work in an enhanced mode, “serving” two organisms - maternal and child.

During pregnancy, the state of the skeletal system also changes. She loses a large amount of calcium, which is used for the full development and growth of the fetus.

Changes in the work, as well as the size and location of the internal organs during the bearing of a child are natural. Often such transformations bring physical discomfort to a woman. But all these are temporary phenomena. A short time after childbirth, the work of all internal organs, their size and location will return to normal.

Specially for -Ksenia Boyko

It is hard not to notice that a woman waiting for the birth of an heir is changing. But these changes are not only external. What happens inside the body? How do individual organs and systems of a woman react to the birth of a new life? Is the load too big? Let's talk about this now.

"Strength test" and weight gain

From the first days, the fetus needs oxygen and nutrients. The mother's body itself begins to gradually prepare for childbirth and breastfeeding the baby. New tasks affect almost the entire body of the mother: the structure of organs during pregnancy changes somewhat, and their functionality expands. These changes are programmed by nature, but this does not make them less tangible. The load on the mother’s body increases significantly, becoming a kind of “strength test”. Those organs that used to work on the verge of normal may fail. Having supported the mother's body in time, we get a certain margin of safety for the fetus.

Not only the location of organs during pregnancy changes, but also body weight, an increase of 10-12 kg for all 9 months is considered the norm. But the initial indicators should also be taken into account, first of all, BMI - body mass index, that is, a harmonious ratio of weight and height.

Breasts and genitals during pregnancy

The most pronounced changes are noted in the system of the genital organs of the expectant mother. The genital organs during pregnancy are transformed according to the growth of the embryo. First of all, this is noticeable in the example of the uterus, which not only constantly increases in size, but also changes its shape from pear-shaped in the first weeks to rounded, and then ovoid. Mucus accumulates in the cervix, and it is no coincidence: later it will help the baby move more easily through the birth canal. The vascular system of the uterus is also undergoing changes, it is replenished with new large blood vessels, which significantly improves the process of supplying the placenta with nutrients and oxygen. The ovaries enlarge and change position.

Changes in the mammary glands are a response to the need to prepare for future lactation. They occur in parallel with hormonal changes, leading to an increase in the production of such significant hormones as progesterone, prolactin, and estrogen. By the end of the term, the mammary gland begins to produce colostrum.

Skeleton and muscular system

Not only the internal organs are rebuilt during pregnancy. The skeletal system of a pregnant woman is affected by an increase in the concentration of relaxin and progesterone in the blood, and these hormones, in turn, contribute to the process of calcium leaching. This microelement is not just taken from the mother's skeleton, calcium is used to form the bone tissue of the fetus. In this case, another physiological reaction occurs: the pelvic bones and their joints become more elastic, which contributes to the non-traumatic progress of the child through the birth canal. The danger is the leaching of calcium from the spine and bones of the foot. To avoid flat feet, it is important to choose the right shoes: with low heels, with arch support. And wearing a bandage and special gymnastics will help the spine.

The cardiovascular system

During the period of bearing a child, the volume of blood in the vessels of a woman increases significantly: by one and a half liters. Accordingly, the intensity of the cardiovascular system also increases. The pulse becomes faster, the contraction of the heart is forced to throw more blood into the aorta. The venous system is the most vulnerable in this period. Varicose veins become a frequent complication, and not only because of the increasing weight load on the lower limbs.

A significant role is played by the deformation of the inferior vena cava, which is responsible for collecting blood from the uterus, pelvic organs and legs. This vessel is located to the right of the spine, and when a woman sleeps on her back, it is compressed. The greater the body weight, the stronger the circulatory disturbance in the organs listed above. That is why expectant mothers are not recommended to sleep in the supine position, but the use of a pillow placed under the legs contributes to freer blood flow. In addition, the increase in the mass of erythrocytes somewhat lags behind the overall increase in blood volume, while blood viscosity decreases. To improve the composition of the blood, mothers are prescribed iron supplements.

Respiratory, digestive and other systems

The development of the fetus requires more and more oxygen, so the volume of air inhaled by a woman increases. Breathing quickens, but this is not critical for the mother's body, since progesterone relaxes the smooth muscles of the bronchial walls, which causes the airways to become wider.

The location of the organs changes somewhat during pregnancy due to the pressure of the fetus on the abdominal cavity. But this is not the only reason for the ongoing changes. Progesterone, which reduces the level of intestinal motility, has a serious effect on the digestive organs. In parallel, the glands begin to secrete more saliva, and the concentration of hydrochloric acid decreases. This manifests itself in the appearance of heartburn and a tendency to constipation. Some malfunctions also occur in the functionality of the gallbladder, bladder, kidneys, but they are also temporary.