What is the placenta, when is it formed and what functions does it perform? When the placenta is formed during pregnancy, the norm and pathology of development. How long does the placenta form during pregnancy.

The placenta is a unique structure. It is formed during embryogenesis and fetal growth, and then ends its existence during childbirth. At the time of its existence, this formation simultaneously belongs to both the mother’s body and the fetus. Let's consider how and over what period of time this amazing organ is formed and why it is needed.

What is it and what does it look like

The placenta (also called the “baby place”) is an organ that is formed during the growth and development of the fetus. Translated from Latin, this term means “cake,” which accurately conveys the features of its appearance.

It is a formation that is limited by two plates: basal (facing the wall of the uterus) and chorionic (facing the fetus). Between these plates are the chorionic villi and intervillous space.

The figure schematically shows its structure.

In the child's place after its rejection, two surfaces are distinguished: internal (adjacent to the fetus) and external (maternal). The fruit surface is smooth and shiny, with blood vessels running underneath it. The maternal surface is grayish-red, divided into lobules, which consist of many branching villi.

How does the placenta form?

When the egg is fertilized, the process of division begins. Over the course of 7-10 days, the embryo slowly moves through the fallopian tube, passing successively through several stages of development.

During this division, the embryo reaches the uterine cavity. Some of its cells are capable of producing special enzymes that dissolve the mucous layer of the uterus and allow the embryo to penetrate it for further development.

The cells of the future placenta are actively dividing and forming a villous membrane around the embryo, which is all riddled with blood vessels. Thanks to this structure, an exchange occurs between the blood of the mother and the unborn baby.

Thus, a full-fledged placenta is formed only at the 5-6th week. Its formation ends at 8-9 weeks, but a complete transition to the placental blood supply occurs only at 15-16 weeks. In this regard, we can generally say that the formation of this structure occurs from 5 to 16 weeks.

Where is the placenta located

If pregnancy develops without anomalies, then the placenta is usually located in the upper parts of the uterus, often on its back wall, and less often on the front. Sometimes it is located in the area of ​​the bottom and pipe corners. The location of this organ in other places does not affect the growth and formation of the unborn child.

Its structure undergoes a number of changes as it adapts to the growing needs of the fetus. At 35-36 weeks it reaches its final development and full functional maturity. By this time, its weight is 500-700 grams, and its diameter is 14-18 cm.

At week 37, the processes of physiological aging of the placenta begin. Its villi undergo degeneration, and calcium salts begin to be deposited in it. So, gradually the woman’s body prepares for childbirth and rejection of the child’s place.

The inner surface of the placenta facing the fetus.

What is the placenta for?

The functions of this organ are diverse. It maintains the normal course of the entire pregnancy and provides the fetus with the necessary substances:

1. The placenta synthesizes hormones (placental lactogen, etc.), in particular progesterone, which maintains the normal course of pregnancy and prevents the uterus from contracting ahead of schedule.
2. This organ ensures gas exchange for the unborn baby: oxygen from the mother’s blood penetrates through the placenta into the blood vessels of the fetus, and carbon dioxide goes into the mother’s blood, after which it is removed from her body.
3. The fetus receives all the necessary nutritional components thanks to this formation.
4. Removal of harmful metabolic products also occurs through it.
5. Formation of immune defense: protective antibodies of the mother are transferred to the fetus. At the same time, the placenta does not allow those cells to pass through that can destroy the fetus by recognizing it as an immunologically foreign object.

Important! Despite its pronounced protective role, it is powerless against viruses, alcohol and other toxic substances. Therefore, the expectant mother needs to be careful about her lifestyle and health during this period.

What do experts pay attention to when it comes to the placenta?

Parameters of this organ based on data. This is a safe research method, which at certain stages of pregnancy is indicated for absolutely all women expecting a baby. The doctor evaluates:

1. Place of attachment. Anomalies include low location and placenta previa. They speak of a low location in cases where it is located at a distance of 6 cm or less from the internal os of the uterus. If this moment is determined in the 1st-2nd trimester, then there is practically no reason for concern, because the placenta can move and will take its usual place closer to childbirth.

Presentation is a dangerous diagnosis, which indicates that the placenta is located in the lower parts of the uterus and covers the internal os, i.e. potential place for the baby to be born.

1. Degree of maturity. Based on ultrasound parameters, the degree of maturity of this organ is assessed. Normally, it happens like this: up to 30-31 weeks, 0 degree of maturity is considered normal. 28-34 weeks - 1 degree of maturity, from 36 weeks 3 or 4 degrees are determined, i.e. physiological aging of this organ occurs. Premature aging of the placenta interferes with the normal formation of the fetus and can cause developmental delays and other problems.
2. Dimensions. For the normal course of pregnancy, its thickness is important, which should be 2-4 cm by 35-37 weeks.

After childbirth, this organ is rejected on its own within 15-20 minutes. The placenta must be examined by a specialist to make sure that there are no slices or pieces left in the uterus, which in the future can cause the development of an infectious process or severe bleeding. If after birth a defect is discovered in it, then diagnostic curettage is performed to remove the remains of the placenta and prevent dangerous complications.

The formation of the placenta begins almost from the first weeks of fetal development. It provides the future baby with everything necessary and helps him grow and develop. Having fulfilled its role, this formation ages and is rejected, and a baby is born who is now able to live without this amazing organ.

I came across an informative article about the placenta. Maybe someone will be interested.

The placenta begins to form within a week after conception, and half an hour after birth, having completed all its functions, the placenta “retires.”

What is the placenta, and why is monitoring its development as important as monitoring your baby's growth?

As soon as the nimble sperm has reached its desired goal, as soon as the egg begins to divide and grow, it appears together with the baby in your body. new organ - placenta, the link between mother and child. After conception, the body produces enzymes that loosen the inner mucous membrane of the uterus, and a small cavity filled with blood appears in its wall - this is where the fertilized egg descends. From now on, she will receive oxygen and nutrition directly from the mother’s body, and after 12-16 weeks, the bodies of mother and baby will begin to communicate directly through the placenta - the baby’s first “house”. It will grow with your baby, satisfying all his vital needs.

Functions of the placenta

• Connection
  The placenta connects mother and child, attaching one side to the walls of the uterus with the help of thin villi, and the other “side”, the vessels of the umbilical cord, to the child. Thus, it ensures close interaction between native organisms.
• Barrier
  The placenta allows protective substances from the mother's blood to enter the baby's body, providing the baby with immunity. At the same time, it protects it from the penetration of some toxins, components of medications (not all), as well as aggressive antibodies from the mother. It prevents the mother’s body from perceiving the fetus as a foreign body and rejecting it. Unfortunately, the placental barrier is easily overcome by drugs, alcohol, nicotine, components of many medications and viruses.
• "Air conditioner"
  One at a time blood vessels of the placenta oxygen flows to the baby, and through the “neighboring” ones, carbon dioxide is released into the mother’s body.
• "Cook"
  Nutrients are filtered from a woman’s blood through the cells of the placenta - in such a “ready” and easily digestible form they reach the baby. Through neighboring vessels of the placenta, the child “returns” into the mother’s blood everything that his body has not absorbed (waste products).
• Security
  It is in the placenta that progestins, estrogens, and hCG hormones are produced, which are necessary for gestation of the fetus, its development and the normal course of pregnancy.

How the placenta develops

Until the eighth week, the chorion, the precursor of the placenta, develops. All the necessary hormones are still produced by the corpus luteum (the place where the egg used to be). The embryo is nourished by the resources of the egg.

7-8 weeks. The hormonal production of the corpus luteum begins to decline, and the developing placenta takes over its function. The embryo is nourished by the uterus.

9-10 weeks. The placenta takes on the function of controlling the metabolism of the mother's body, provoking in it the changes necessary for the life of the developing fetus. Toxicosis in the mother may intensify.

11-12 weeks. The embryo “becomes” the fetus. The formation of the placenta is not yet complete, but the baby receives nutrition from the mother’s blood.

15-16 weeks. The formation of the placenta ends. At this time, by determining the level of the hormone estriol in the urine, it is possible to evaluate the functioning of the fetoplacental complex (placenta-fetus system).

What doctors want to know about the placenta

Degree of maturity of the placenta

This parameter, as doctors say, is “ultrasonic,” that is, it depends on the density of placental structures determined by ultrasound examination.

There are four degrees of placental maturity:

• Normally, up to 30 weeks of pregnancy, a zero degree of placental maturity should be determined;
• the first degree is considered acceptable from the 27th to the 34th week;
• the second - from 34th to 39th;
• starting from the 37th week, the third degree of maturity of the placenta can be determined.

At the end of pregnancy, the so-called physiological aging of the placenta, accompanied by a decrease in the area of ​​its exchange surface and the appearance of areas of salt deposition.

Placenta insertion site

Determined by ultrasound (see above for the location of the placenta in uncomplicated pregnancy).

Placenta thickness

It is also determined through ultrasound examination - placentometry: after establishing the placenta attachment site, the area where it has the largest size is found, which is determined. The thickness of this organ, as already mentioned, continuously increases until 36-37 weeks of pregnancy (by this period it ranges from 20 to 40 mm). Then its growth stops, and in the future it either decreases or remains at the same level.

In anticipation of childbirth, expectant mothers associate all their worries and fears primarily with the child, however healthy placenta, as the main “battery” for the developing fetus, is no less important. Often, pregnancy complications are associated specifically with the child's place. And yet you should not be afraid of abnormalities in the placenta: even if the doctor discovers any abnormalities in you, it is undoubtedly easier to correct the situation and influence this “temporary organ” than the child himself.

If your doctor suspects you...

• Placenta previa, this means that the placenta is located at the bottom of the uterus, as if blocking the entrance (normally it should be located on one of the walls of the uterus).
  So what now? The baby is in no danger of such a deviation. The most important thing is not to provoke bleeding, which is where the uterus is located during placenta previa. Alas, you will have to postpone sexual activity, and also postpone visiting the sauna, taking hot baths and reduce physical activity to a minimum. It is better to go to the maternity hospital 1-1.5 weeks before the expected date of birth.
  How will we give birth? Placenta previa can be partial or complete. If complete, a cesarean section is indicated. If the presentation is partial, then the decision about the operation is made by the doctor depending on how the placenta is located.
• Placenta accreta.
  The villi that attach the placenta to the walls of the uterus are usually connected to its inner mucous membrane, and at the time of birth they easily peel off from the walls. But it happens that they penetrate into deeper muscle layers. This anomaly is quite rare.
  So what now? You will have to limit physical activity and sex life.
  How will we give birth? Since such a diagnosis can most often be made only at the time of birth, the first periods proceed naturally, and in the third phase, after the baby is born, the obstetrician will have to separate the placenta manually. This is done under general anesthesia and you will not feel anything.
• Placental insufficiency.
  If the blood circulation of the mother's blood vessels is impaired, there is a risk that the baby will not receive the necessary nutrition and the placenta will not be able to fully protect him from harmful external influences. This diagnosis can be made from 8 weeks of pregnancy; diagnosed by ultrasound or Doppler study of blood vessels.
  So what now? To improve blood supply to the fetus, mothers are recommended to take frequent and long walks, a set of exercises and a course of treatment to improve blood supply to the placenta (thermal procedures in the perinephric area, magnesium electrophoresis; taking vasodilators and beta-mimetics, heparin therapy). In addition, a diet rich in protein (fish, cottage cheese and dairy products, boiled meat) is prescribed.
  How will we give birth? Normally, naturally. However, be prepared for the fact that you will have to go into confinement and undergo a course of special therapy.
• Premature placental abruption.
  Any period that begins before the third phase of labor can be considered premature. It is diagnosed by a doctor based on the results of the study. Symptoms that you need to pay attention to are sharp pain in the lower abdomen, bleeding from the vagina, a sharp drop in temperature and pressure against the background of pallor, shortness of breath, sweating and increased heart rate. This pathology often has hereditary roots, so ask your mother if she had such a problem.
  So what now? You need to go to the hospital and undergo a course of therapy.
  How will we give birth? If placental abruption began during labor before the third stage, you will most likely be offered a cesarean section.
• Placental infarction.
  This term is also called necrosis, that is, necrosis of an area of ​​the placenta. In this case, the blood supply to the placenta deteriorates, and the baby may not receive enough nutrition and oxygen.
  So what now? Medicines that improve blood circulation and additional nutrition will help activate the “working” areas of the placenta.
  How will we give birth? You need to prepare yourself psychologically for a caesarean section. When choosing a maternity hospital, focus on those with intensive care wards for newborns and the most modern equipment.
• Premature aging of the placenta.
  Towards the end of pregnancy functions of the placenta gradually weaken. Your baby is getting ready to be born, and his first “house” is reaching its end to go to “retirement.” But it happens that the aging process of the placenta begins too early, and the placenta can no longer provide the child with all the necessary substances. Expectant mothers who smoke and are addicted to diets are prone to this.

So what now? In 9 cases out of 10, the doctor will send you for preservation. At home, if the placenta matures rapidly and wears out, you may be prescribed medication (Curantil, Trental).

How will we give birth? In most cases, childbirth occurs naturally, however aging placenta may begin to peel off ahead of schedule, and then you will be offered a cesarean section.

The birth of a child is such an important event that nine months of pregnancy is not enough to read all the books, watch all the educational films and attend all the seminars that inform about its features. And yet, the future parents of the baby, even if they have already managed to raise more than one of his older brothers and/or sisters, every time, like for the first time, they worry and absorb any useful information. The opportunity to find out the gender of your unborn child is one of those things that worries you no less than choosing a name for it. This inspires you on the eve of a new addition to the family and allows you to plan your own actions, purchase clothes, toys and furniture for the newborn.

Therefore, one should not consider interest in who will be born, a boy or a girl, as idle and useless. In fact, it has many practical benefits and allows mom and dad to perceive the unborn little person as a full-fledged member of the family, treat him with conscious love and begin their communication with him. Only some couples try to predict the gender of the future heir and come up with ways to influence his formation. And others are limited to the advance determination of the gender of the fetus formed in the mother’s womb. But in any case, it will be useful for both to know how the sex of a child is formed and what determines it.

Genetics of sex and its laws
The fetus matures in the mother's body for approximately forty weeks (an average of 270 days), gradually turning from a fetus into an embryo. The nine-month pregnancy period is usually divided into so-called trimesters, that is, three phases lasting three months each. During each trimester, certain changes in the fetus, characteristic of this stage of embryonic development, occur, by which the duration and some features of the course of pregnancy can be determined. Moreover, the entire period of pregnancy is also usually divided into two main stages: embryonic (fetal) and fetal (fetal).

Since the cause of pregnancy is the fusion of male and female germ cells that have a different set of chromosomes, the sex of the unborn child depends on this set. But each egg always contains only X chromosomes, while each aspermatozoon contains both X and Y chromosomes (in a ratio of approximately 50/50). So the sperm (in the case of the X chromosome, a female child will be born, and in the case of the Y chromosome, a male child) determines which sex of the organism will develop from the blastocyst (the result of the division of a fertilized egg). Thus, the fetus becomes a “boy” or “girl” almost immediately after conception.

1. The fetal organs begin to form during the first trimester of pregnancy. Including the primary germ cells, which are associated with the secretions of the gonads approximately in the fifth week after conception.
   
2. The genitals of the embryo acquire a more characteristic appearance in the sixth week of development. But still, they are still so undeveloped that it is not yet possible to study them using ultrasound or another method. Although the testicle is already beginning to form. But reproductive organs, that is, testes and ovaries, develop later: in the seventh week after conception.
   
3. Only during the eighth week of pregnancy does the unborn boy acquire obvious male sexual characteristics. This happens because, under the influence of the Y chromosome, the testicles begin to produce the hormone testosterone. Accordingly, primary germ cells are produced, as well as the urogenital and anal areas.
   
4. But for now these are internal organs, and the external genitalia will take shape only in the ninth week, and they can certainly be identified starting from the twelfth week after conception.
   

Determining the sex of the child
A study using an ultrasound probe, or ultrasound for short, allows you to “see” the gender of an unborn baby. Of course, the main task of this diagnostic method is different, and in general the range of its capabilities is much wider. Ultrasound shows the general condition of the fetus and makes it possible to identify possible defects and pathologies in its development as early as possible. And it is possible to find out the gender if the fetus is positioned correctly in the womb. The thickness of the abdominal wall of a pregnant woman and the amount of amniotic fluid also affect both the accuracy and the very possibility of determining the sex of the child.

Theoretically, ultrasound can identify a boy or girl from the 11th week of their intrauterine development, but such an early diagnosis has a high risk of error. Therefore, it makes sense for even the most curious and impatient parents to wait at least until the 12th week of pregnancy. What happens if you try earlier? Nothing terrible, but no benefit either. The genital tubercle, which looks like a small bulge on the body of the embryo, does not appear until the sixth week after conception. But up until the ninth week, the genitals of boys and girls look completely identical. There are only so-called labial-scrotal folds, rounded and indistinguishable from each other in appearance.

After approximately the 11th week of intrauterine development, the boy’s penis and scrotum begin to “emerge” from these folds. But the testicles are still located in the abdomen, and they will remain there until the seventh month of pregnancy. So at the 11th week, using an ultrasound, you can make certain assumptions, but you need to be prepared for the fact that the probability of error is at least 50%. And only 5 or even 6 weeks after the formation of the genital organs begins, external sexual characteristics will appear clearly enough for the ultrasound sensor not to make a mistake.

Usually, the first ultrasound scan during pregnancy is prescribed to the expectant mother no earlier than the 12-13th week of pregnancy. But even then, it is still very difficult to discern the gender of the embryo. At the 15th week, the probability of a successful study is higher, but only by the 18th week will the diagnostician be able to give you some reliable information. Moreover: if by this time the boy can already be properly examined, then with the development of a female embryo, parents sometimes have to remain in the dark until the 20th or even the 25th week of pregnancy.

This is due to the peculiarities of the development of the labia majora in the early stages. They are often in a state of swelling and therefore can be easily confused with the male genital organ. In addition, the fetus may lie with its legs tightly clenched and thus not allow one to see its genitals. And sometimes fingers or toes and even the umbilical cord are mistakenly mistaken for the penis. So future parents can be advised to be patient and wait until the 24th week of pregnancy. By this time, the fetus will already be quite mobile, will take the correct position and will certainly demonstrate its gender.

The placenta is the most important organ that is responsible for the proper development of the baby in the womb. When the placenta is fully formed, the baby receives his first house (not without reason), which, on the one hand, makes it possible to receive everything necessary for growth and development, and on the other, protects its little owner from harmful toxins and other not entirely useful substances found in the mother’s body . In addition to providing the fetus with useful substances, the placenta is responsible for the supply of oxygen and the removal of waste products.

Formation of the placenta during pregnancy

It is difficult to determine exactly the time when the placenta begins to form, because the initial stage can be attributed to the 7th day after conception. At this moment, the embryo crashes into the uterine mucosa, located in the so-called lacuna, which is filled with maternal blood. At this time, the chorion develops - the outer membrane of the fetus, which can confidently be called the precursor of the placenta.

15-16 weeks of pregnancy - this is the period at which the placenta is formed. By week 20, when the organ is ready to function independently, the formation of the placenta is completely completed.

During a normal pregnancy without any complications or pathologies, the placenta forms along the back or front wall of the uterus. The timing of the formation of the placenta is determined by the individual characteristics of the body, but, as a rule, by the 36th week of pregnancy, the organ reaches its functional maturity. Immediately before birth, the placenta is 2 to 4 cm thick and reaches 18 cm in diameter.

Placenta after birth

Regardless of how many weeks the placenta is formed, during pregnancy the organ experiences 4 stages of maturity. Surprisingly, before birth, the placenta is in a state of physical aging - its size decreases slightly, and salt deposits appear on the surface. This is the fourth.

After birth, the placenta separates from the walls of the uterus on its own within 15-20 minutes. In some cases, a longer period of up to 50 minutes may be required. The doctor should carefully examine the integrity of the placenta to make sure that there are no fragments left in the uterus that could cause inflammation. Then the placenta is sent for morphological examination, based on the results of which the course of pregnancy and the causes of possible deviations can be assessed.

Biological and social factors influencing gender identification are so closely related that it is difficult to understand them. When a child is born to parents, in modern times it is already known in advance what gender it will be, but if the mother did not know this before giving birth. What a thirst she would have then to find out the sex of the baby as quickly as possible. This happens because parents treat their children differently depending on their gender. Thus, the behavior of mom and dad gives the child an incentive to learn more about himself by identifying himself by gender.

After conception, the process of formation of sexual characteristics in the embryo occurs. Having united, the female and male cells combine their chromosomes, 23 each from the sperm and egg into a new organism. This gives a total of 46 chromosomes. A female cell always carries an X chromosome, and a male spermatozoon either Y or X. Thus, the female code is XX, and the male XY is male.

Further in the development of the embryo, the stage of formation of the gonads takes place. This occurs in the sixth week of pregnancy. Before this period, it is impossible to determine the fetus. A male embryo occurs when a male chromosome is present. Here there must be an antigen H-Y antigen, which is responsible for the male genetic code. The absence of this antigen indicates that the sex of the child will be female.

The appearance of the genital organs occurs after the stage of formation of the gonads with the help of hormones. This stage begins at 8-9 weeks of pregnancy. When the amount of testosterone is produced more, the gender is determined to be male. Both female and male bodies contain hormones of both sexes, however, a greater amount of a particular hormone indicates a specific gender.

The process of intrauterine development of the fetus involves the influence of androgens on it (hormones that play a decisive role in the occurrence of secondary sexual characteristics in both one and the other sex, for example, a rough voice, “vegetation” on the face and the whole body. As in all men, increased secretion sweat, elongation of the penis, formation of the face and body skeleton according to the male type, increase in the size of the prostate and the amount of its secretion). If androgens do not have a sufficient effect on the fetus, then a girl will be born. In the first period, the formation of the genital organ occurs. Then comes the creation of the brain's sexual orientation. The stage of formation of the male or female hypothalamus is underway.

Laying of external organs

Laying the internal organs:

1. During the initial 6 weeks of pregnancy, male and female embryos cannot be distinguished;
2. Only after 8 weeks of pregnancy, the testes of an embryo with the sexual characteristics of a boy release testosterone and an inhibitor of the Müllerian ducts, leading to the disappearance of the ducts themselves. In the absence of male hormones, the Müllerian ducts (a double canal with a connected distal part, which appears after the end of the second month of development of the embryo inside the mother from the grooves that perform the demarcating role of the epithelium) begin to transform into female organs. The Wolffian ducts (structures in the fetus that subsequently develop into the male genital organs located inside) cease to exist.
3. After 9 months of pregnancy, in the female fetus, the Müllerian duct turns into the fallopian tubes, and in the male fetus, the glands turn into the scrotum.

Video of how the sex of a child is determined

There is no limit to the uniqueness of a woman’s body. And first of all, I admire the ability not only to conceive, to be a repository for the development of the fetus, but also the ability to reproduce even a new organ - the placenta.

Scientists have proven that the placenta is a rich source of unique biologically active substances, which has amazing properties of tissue restoration, immune regulation, neuroprotective effects, anti-inflammatory, anti-allergic and even anti-tumor. And this is not to mention the widespread use of placenta extract in cosmetology.

What does it represent?

Questions often arise about how and when the placenta is formed during pregnancy, what pathologies may arise and what to do in this case. To answer them you need to have an idea of ​​what it is.

The placenta is an organ that can belong to two organisms at the same time. The life support of the growing fetus depends on the development and position of the placenta in the uterine cavity; it is also called the “baby place” and temporary, since at birth its activity stops and is rejected by the mother’s body.

Morphologically, the organ is an accumulation of certain cells - the chorion, outgrowths of the embryonic membranes that grow into the uterus. During pregnancy, parts of the chorion grow and begin to resemble the placenta. By the end of the 12th week, formation is completed. And it looks like a disk or flat cake (this is the meaning from the Latin “placenta”).

One part of the placenta is connected to the uterus, and the other is directed towards the fetus. They communicate with each other via the umbilical cord. Inside it, it has two arteries and one vein. Arteries deliver oxygenated blood and nutritional molecules, and veins will return all waste substances. The length of the umbilical cord is 50–55 cm.

Main functions

The placenta is not just an organ that connects two organisms. She faces several challenges:

1. Respiratory function. Responsible for gas exchange between mother and fetus.
2. Trophic, or nutritional. Delivers all the necessary substances for nutrition (protein, water, vitamins, microelements).
3. Protective. Protects from the negative effects of the environment and microorganisms, but has a throughput capacity for viruses, toxic substances, poisons and drug molecules.
4. Immune function. The organ suppresses the immune conflict of two genetically foreign organisms - mother and fetus.
5. Endocrine. The afterbirth produces hormones (estrogen, human chorionic gonadotropin, placental lactogen, progesterone, prolactin and cortisol). It also promotes the transport of hormones from mother to fetus (adrenal, sex and thyroid hormones).

The correct functioning of the entire mother-placenta-fetus system contributes to the full growth and formation of the child throughout the entire period.

Formation and arrangement

The afterbirth, like the fetus, goes through several stages of formation. Doctors monitor its location, growth and movement throughout the entire gestation period. This allows you to timely prevent and eliminate possible complications.

Normally, the attachment site is the area of ​​the fundus or walls of the uterus. As a rule, the afterbirth is located along the back wall.

The location of the placenta is important when it is located in the lower segments of the uterus. This position is called presentation. It can be complete or partial.

The danger of this pathology is that the placenta closes the internal os and prevents the passage of the fetus during delivery. Also, the danger lies in the occurrence of detachment and bleeding with a fatal outcome for the fetus or severe brain hypoxia.

With complete presentation, independent delivery is impossible. Doctors perform surgery without fail.

But at the same time there is one significant advantage. The placenta has one amazing property - it is able to move (migrate) towards better blood supply and nutrition, that is, to the fundus of the uterus. The placenta rises with the growing uterus.

The structural structure of the organ changes throughout pregnancy and fulfills all the needs of the baby. At 35 weeks, the placenta becomes mature.

Maturation

The process of growth and development of the placenta throughout pregnancy is called maturation. The maturity of the placenta and its compliance with the term are monitored using ultrasound.

Generally accepted classification by degree of maturity:

• 0 - up to 30 weeks.
• 1 - 30–34 weeks.
• 2 - 34–37 weeks.
• 3 - 37–39 weeks.
• 4 - before childbirth.

The degree of maturity of the placenta may indicate the presence of pathologies in the woman’s condition. The deviation is manifested by a discrepancy with the gestational age. Thus, a prematurely ripened placenta occurs due to disruption of placental blood flow due to late toxicosis or anemia. But there are exceptions, for example, a woman’s genetic predisposition.

A lesser degree of maturity is not considered a deviation. The most important thing is that the child’s development and condition do not suffer.

Normal parameters of the placenta at 35 weeks:

1. Thickness - 3.5–4 cm.
2. Weight - 500 gr.
3. Diameter - from 18 cm to 25 cm.

By the time of birth, the placenta decreases in size.

There are a number of methods to determine the functional state of the placenta. One of them is based on the placental ability to secrete the hormone lactogen (it is able to inform about the well-being of the placenta). During pregnancy more than 30 weeks, its concentration should be more than 4 mcg/ml. If the indicator is below this norm, this most likely indicates a violation of placental function.

There is also a method for daily monitoring of estrogen or estriol excretion in urine. Low levels of these substances in urine and plasma indicate severe liver damage, intra-hepatic cholestasis or antibiotic use. If there is a low level of estriol in the urine and a high level in the plasma, then the cause of this will be renal failure with impairment of its functions.

Placenta department

The birth of the placenta is the next stage after the birth of the baby. Its separation and expulsion occurs within 5–20 minutes. This period is called the successive period.

Placental abruption begins with a reduction in the placental area (this is the area where the placenta is attached to the uterus by the vasculature). With each uterine contraction, the placental area becomes smaller, and the afterbirth is separated from the wall. After confirming complete detachment, the doctor asks the postpartum woman to push. With complete separation, the afterbirth is born painlessly.

After removing the placenta, the placenta is examined for damage. It is imperative to remove all residues. Typically, this procedure (manual examination of the uterine cavity) is performed by an experienced specialist under short-term general anesthesia.

Then the condition of the placenta is examined. It indicates the course of pregnancy (infectious processes, premature placental abruption, calcifications). This information is more necessary for pediatricians to assess the characteristics of the baby’s condition.

There are exceptions when the placenta has no visible defects and the pieces remain in the uterine cavity. The consequences of this phenomenon are not long in coming. Within 7 days, the woman’s bleeding increases, pain appears in the lower abdomen, and sometimes the body temperature rises to 37–38 degrees. In this case, it is necessary to go to the hospital and conduct an ultrasound examination. After establishing the cause and localization of the residue, curettage of the uterine cavity is performed to remove a piece of the placenta and eliminate bleeding. Antibacterial and antianemic therapy is prescribed.

Pathologies of organ development

The placenta may not form correctly. But don't worry right away. Not all pathologies have a negative impact on fetal development.

Fetoplacental insufficiency

This is a functional disorder in the functioning of the placenta with a change in its size, manifested by insufficient delivery of nutrients to the child against the background of chronic oxygen deficiency. This symptom complex is the main reason for developmental delay. That is, organs are formed incorrectly.

It is better to prevent this condition even when planning a child: carry out thorough preparation and treatment of chronic diseases. During the entire gestation period, it is necessary to monitor glycemia, blood pressure, and avoid infectious diseases.

It is impossible to completely cure placental pathology, but there are medications that improve blood flow and nutrient transfer in the mother-placenta-fetus system. Therapy is carried out strictly under the supervision of the attending physician.

Incorrect structure

Changes occur in the morphological structure of the placenta. Normally, it is a platform with equal (15 to 20) lobes located on it. They are separated by partitions from each other. But there are cases when the placenta is represented by only two large lobes or another additional lobe is attached to the normal placenta. There is a type of “fenestrated” placenta - it contains islands covered with a membrane and resembling windows.

Such changes in morphology are determined genetically or are a consequence of pathology of the uterine mucosa. Changes in structure do not have much effect on the fetus. But during childbirth, such an afterbirth can bring a lot of problems during the period of birth. Most often, it is difficult to peel off and requires manual removal under anesthesia.

It is important to warn the obstetrician-gynecologist about this anomaly in the structure of the placenta - this can prevent further complications in the form of bleeding or infection.

Symptoms of pathology

Early diagnosis and timely assistance can improve the outcome of the situation. Therefore, it is very important to monitor unusual sensations and promptly report them to your doctor. Maybe:

• Bleeding.
• Drawing or sharp pain in the abdomen.
• Hypertension.
• Severe swelling throughout the body.
• Urinary retention.
• Headaches and dizziness.
• Cramps.

All these are alarming symptoms and indications for hospitalization for a pregnant woman.

Manifestations of placental pathologies:

1. Underdeveloped/overripe.
2. The only artery of the umbilical cord.
3. Premature detachment.
4. Thrombosis inside the placenta.
5. Pathologies in the lobular structure.
6. Inflammation.
7. Increment to the uterus.
8. Increase in thickness.
9. Low placentation (at the cervical pharynx).
10. Tumors or cysts.
11. Infarction of the placenta area.

These pathological changes occur due to diabetes mellitus, atherosclerotic changes, late toxicosis, infection of bacterial and viral etiology, Rh conflict between mother and fetus, severe anemia, and preeclampsia. Problems can also be caused by bad habits, obesity, and congenital defects.

Pathological changes in the placenta are easier to prevent than to treat. And first of all, a woman has the power to eliminate all negative factors. So, every expectant mother, while carrying a child, must be observed by a doctor and undergo routine examinations (ultrasound screening, routine tests).

It is necessary to be careful and attentive to your own health and well-being, and promptly report negative symptoms to your gynecologist.

After implantation, the trophoblast begins to grow rapidly. The completeness and depth of implantation depends on the lytic and invasive ability of the trophoblast. In addition, already during this period of pregnancy, the trophoblast begins to secrete hCG, PP1 protein, and growth factors. From the primary trophoblast, two types of cells are distinguished: cytotrophoblast - the inner layer and syncytiotrophoblast - the outer layer in the form of a symplast, and this layer is called “primitive” or “previllous forms”. According to some researchers, in the previllous period the functional specialization of these cells is already revealed. If the syncytiotrophoblast is characterized by invasion deep into the endometrium with damage to the wall of the maternal capillaries and venous sinusoids, then the primitive cytotrophoblast is characterized by proteolytic activity with the formation of cavities in the endometrium, where maternal red blood cells enter from the destroyed capillaries.

Thus, during this period, numerous cavities appear around the submerged blastocyst, filled with maternal red blood cells and the secretion of the destroyed uterine glands - this corresponds to the previllous or lacunar stage of development of the early placenta. At this time, active rearrangements occur in the endodermal cells and the formation of the embryo itself and extraembryonic formations, the formation of the amniotic and yolk vesicles begins. Proliferation of primitive cytotrophoblast cells forms cell columns or primary villi, covered with a layer of syncytiotrophoblast. The appearance of primary villi coincides with the first missing menstruation.

On the 12-13th day of development, the transformation of primary villi into secondary villi begins. At the 3rd week of development, the process of vascularization of the villi begins, as a result of which the secondary villi turn into tertiary ones. The villi are covered with a continuous layer of syncytiotrophoblast and have mesenchymal cells and capillaries in the stroma. This process occurs along the entire circumference of the embryo sac (ring-shaped chorion, according to ultrasound), but to a greater extent where the villi come into contact with the implantation site. At this time, the layer of provisional organs leads to the bulging of the entire embryo sac into the lumen of the uterus. Thus, by the end of 1 month of pregnancy, the circulation of embryonic blood is established, which coincides with the beginning of the embryo’s heartbeats. Significant changes occur in the embryo, the rudiment of the central nervous system appears, blood circulation begins - a unified hemodynamic system has formed, the formation of which is completed by the 5th week of pregnancy.

From 5-6 weeks of pregnancy, the formation of the placenta occurs extremely intensively, since it is necessary to ensure the growth and development of the embryo, and for this it is necessary, first of all, to create the placenta. Therefore, during this period, the rate of development of the placenta is faster than the rate of development of the embryo. At this time, the developing syncytiotrophoblast reaches the spiral arteries of the myometrium. The establishment of uteroplacental and placental-embryonic blood flow is the hemodynamic basis for intensive embryogenesis.

Further development of the placenta is due to the formation of the intervillous space. Proliferating syncytiotrophoblasts line the spiral arteries, and they become typical uteroplacental arteries. The transition to placental circulation occurs by 7-10 weeks of pregnancy and is completed by 14-16 weeks.

Thus, the first trimester of pregnancy is a period of active differentiation of the trophoblast, the formation and vascularization of the chorion, the formation of the placenta and the connection of the embryo with the maternal body.

The placenta is fully formed by the 70th day from the moment of ovulation. By the end of pregnancy, the weight of the placenta is V, the child’s body weight. The blood flow rate in the placenta is approximately 600 ml/min. During pregnancy, the placenta “ages”, which is accompanied by the deposition of calcium in the villi and fibrin on their surface. Deposition of excess fibrin can be observed in diabetes mellitus and Rhesus conflict, as a result of which the nutrition of the fetus deteriorates.

The placenta is the provisional organ of the fetus. In the early stages of development, its tissues differentiate at a more accelerated pace than the embryo's own tissues. This asynchronous development should be seen as an expedient process. After all, the placenta must ensure the separation of maternal and fetal blood flows, create immunological immunity, ensure the synthesis of steroids and other metabolic needs of the developing fetus; the subsequent course of pregnancy depends on the reliability of this stage. If during the formation of the placenta there is insufficient trophoblast invasion, then an incomplete placenta will form - a miscarriage or delayed fetal development will occur; with defective construction of the placenta, toxicosis develops in the second half of pregnancy; if the invasion is too deep, placenta accreta is possible, etc. The period of placentation and organogenesis is the most responsible in the development of pregnancy. Their correctness and reliability is ensured by a complex of changes in the mother’s body.

At the end of the third and fourth months of pregnancy, along with intensive growth of villi in the area of ​​implantation, degeneration of villi outside it begins. Without receiving adequate nutrition, they are exposed to pressure from the growing fetal sac, lose their epithelium and become sclerotic, which is a stage in the formation of a smooth chorion. A morphological feature of the formation of the placenta during this period is the appearance of dark villous cytotrophoblast. Dark cytotrophoblast cells have a high degree of functional activity. Another structural feature of the villous stroma is the approach of capillaries to the epithelial cover, which makes it possible to accelerate metabolism by reducing the epithelial-capillary distance. At the 16th week of pregnancy, the weight of the placenta and fetus equalizes. Subsequently, the fetus quickly overtakes the mass of the placenta, and this trend remains until the end of pregnancy.

At the 5th month of pregnancy, a second wave of cytotrophoblast invasion occurs, which leads to an expansion of the lumen of the spiral arteries and an increase in the volume of uteroplacental blood flow.

At 6-7 months of gestation, further development into a more differentiated type occurs, high synthetic activity of syncytiotrophoblast and fibroblasts in the stroma of cells around the capillaries of the villi remains.

In the third trimester of pregnancy, the placenta does not significantly increase in weight, but undergoes complex structural changes that make it possible to meet the increasing needs of the fetus and its significant increase in weight.

At the 8th month of pregnancy, the greatest increase in placental weight was noted. There was a complication in the structure of all components of the placenta, significant branching of the villi with the formation of katyledons.

At the 9th month of pregnancy, a slowdown in the rate of growth of placental mass was noted, which further intensified at 37-40 weeks. There is a clear lobular structure with very powerful intervillous blood flow.

Protein hormones of the placenta, decidua and fetal membranes

During pregnancy, the placenta produces major protein hormones, each of which corresponds to a specific pituitary or hypothalamic hormone and has similar biological and immunological properties.

Protein hormones of pregnancy

Protein hormones produced by the placenta

Hypothalamic-like hormones

• gonadotropin releasing hormone
• corticotropin releasing hormone
• thyrotropin-releasing hormone
• somatostatin

Pituitary-like hormones

• human chorionic gonadotropin
• placental lactogen
• human chorionic corticotropin
• adrenocorticotropic hormone

Growth factors

• insulin-like growth factor 1 (IGF-1)
• epidermal growth factor (EGF)
• platelet-derived growth factor (PGF)
• fibroblast growth factor (FGF)
• transforming growth factor P (TGFP)
• inhibin
• activin

Cytokines

• interleukin-1 (il-1)
• interleukin-6 (il-6)
• colony stimulating factor 1 (CSF1)

Pregnancy-specific proteins

• beta1,-glycoprotein (SP1)
• eosinophilic basic protein pMBP
• soluble proteins PP1-20
• membrane-binding proteins and enzymes

Protein hormones produced by the mother

Decidual proteins

• prolactin
• relaxin
• insulin-like growth factor binding protein 1 (IGFBP-1)
• interleukin 1
• colony stimulating factor 1 (CSF-1)
• progesterone-associated endometrial protein

The pituitary triple hormones correspond to human chorionic gonadotropin (CG), human chorionic somatomammotropin (CS), human chorionic thyrotropin (XT), and placental corticotropin (PCT). The placenta produces peptides similar to ACTH, as well as releasing hormones (gonadotropin-releasing hormone (GnRH), corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH) and somatostatin) similar to hypothalamic ones. It is believed that the control of this important function of the placenta is carried out by hCG and numerous growth factors.

Human chorionic gonadotropin, a pregnancy hormone, is a glycoprotein similar in its action to LH. Like all glycoproteins, it consists of two chains, alpha and beta. The alpha subunit is almost identical to all glycoproteins, and the beta subunit is unique to each hormone. Human chorionic gonadotropin is produced by syncytiotrophoblast. The gene responsible for the synthesis of the alpha subunit is located on chromosome 6, for the beta subunit of LH there is also one gene on chromosome 19, while for the beta subunit of hCG there are 6 genes on chromosome 19. Perhaps this explains the uniqueness of the hCG beta subunit, since its lifespan is approximately 24 hours, while the lifespan of betaLH is no more than 2 hours.

Human chorionic gonadotropin is the result of the interaction of sex steroids, cytokines, releasing hormone, growth factors, inhibin and activin. Human chorionic gonadotropin appears on the 8th day after ovulation, one day after implantation. The functions of human chorionic gonadotropin are extremely numerous: it supports the development and function of the corpus luteum of pregnancy up to 7 weeks, takes part in the production of steroids in the fetus, DEAS of the fetal zone of the adrenal glands and testosterone by the testes of the male fetus, participating in the formation of the sex of the fetus. Expression of the human chorionic gonadotropin gene was detected in fetal tissues: kidneys, adrenal glands, which indicates the participation of human chorionic gonadotropin in the development of these organs. It is believed to have immunosuppressive properties and is one of the main components of the “serum blocking properties,” preventing the rejection of the fetus that is foreign to the mother’s immune system. Receptors for human chorionic gonadotropin are found in the myometrium and myometrial vessels; human chorionic gonadotropin appears to play a role in the regulation of the uterus and vasodilation. In addition, human chorionic gonadotropin receptors are expressed in the thyroid gland, and this explains the stimulating activity of the thyroid gland under the influence of human chorionic gonadotropin.

The maximum level of human chorionic gonadotropin is observed at 8-10 weeks of pregnancy (100,000 IU), then slowly decreases and at 16 weeks is 10,000-20,000 IU/I, remaining this way until 34 weeks of pregnancy. At 34 weeks, many note a second peak of human chorionic gonadotropin, the significance of which is not clear.

Placental lactogen (sometimes called chorionic somato-mammotropin) has biological and immunological similarities to growth hormone and is synthesized by syncytiotrophoblast. Synthesis of the hormone begins from the moment of implantation, and its level increases in parallel with the weight of the placenta, reaching a maximum level at 32 weeks of pregnancy. The daily production of this hormone at the end of pregnancy is more than 1 g.

According to Kaplan S. (1974), placental lactogen is the main metabolic hormone that provides the fetus with a nutrient substrate, the need for which increases with pregnancy. Placental lactogen is an insulin antagonist. Ketone bodies are an important source of energy for the fetus. Enhanced ketonogenesis is a consequence of a decrease in the effectiveness of insulin under the influence of placental lactogen. In this regard, the utilization of glucose in the mother is reduced, thereby ensuring a constant supply of glucose to the fetus. In addition, increased insulin levels in combination with placental lactogen provide enhanced protein synthesis and stimulate the production of IGF-I. There is little placental lactogen in the blood of the fetus - 1-2% of the amount in the mother, but it cannot be ruled out that it directly affects the metabolism of the fetus.

The "chorionic growth hormone" or "growth hormone" variant is produced by the syncytiotrophoblast, is detected only in the mother's blood in the second trimester and increases until 36 weeks. It is believed that, like placental lactogen, it is involved in the regulation of IGFI levels. Its biological effect is similar to that of placental lactogen.

The placenta produces a large number of peptide hormones, very similar to the hormones of the pituitary gland and hypothalamus - human chorionic thyrotropin, human chorionic adrenocorticotropin, human chorionic gonadotropin releasing hormone. The role of these placental factors is not yet entirely understood; they may act in a paracrine manner, exerting the same effect as their hypothalamic and pituitary counterparts.

In recent years, placental corticotropin-releasing hormone (CRH) has received much attention in the literature. During pregnancy, CRH increases in plasma at the time of delivery. CRH in plasma is associated with CRH-binding protein, the level of which remains constant until the last weeks of pregnancy. Then its level decreases sharply, and, in connection with this, CRH increases significantly. Its physiological role is not entirely clear, but in the fetus, CRH stimulates ACTH levels and through it contributes to steroidogenesis. CRH is thought to play a role in inducing labor. Receptors for CRH are present in the myometrium, but according to the mechanism of action, CRH should cause relaxation of the myometrium rather than contractions, since CRH increases cAMP (intracellular cyclic adenosine monophosphate). It is believed that the isoform of CRH receptors or the binding protein phenotype changes in the myometrium, which, through stimulation of phospholipase, can increase the level of intracellular calcium and thereby provoke contractile activity of the myometrium.

In addition to protein hormones, the placenta produces a large number of growth factors and cytokines. These substances are necessary for the growth and development of the fetus and the immune relationship between mother and fetus, ensuring the continuation of pregnancy.

Interleukin-1beta is produced in the decidua, colony stimulating factor 1 (CSF-1) is produced in the decidua and in the placenta. These factors take part in fetal hematopoiesis. The placenta produces interleukin-6, tumor necrosis factor (TNF), and interleukin-1beta. Interleukin-6, TNF stimulate the production of human chorionic gonadotropin, insulin-like growth factors (IGF-I and IGF-II) take part in the development of pregnancy. Studying the role of growth factors and cytokines opens a new era in the study of endocrine and immune relationships during pregnancy. A fundamentally important pregnancy protein is insulin-like growth factor binding protein (IGFBP-1beta). IGF-1 is produced by the placenta and regulates the transition of nutritional substrates through the placenta to the fetus and, thus, ensures the growth and development of the fetus. IGFBP-1 is produced in decidua and binding to IGF-1 inhibits fetal development and growth. The weight of the fetus and the rate of its development directly correlate with IGF-1 and vice versa with lGFBP-1.

Epidermal growth factor (EGF) is synthesized in the trophoblast and is involved in the differentiation of cytotrophoblast into syncytiotrophoblast. Other growth factors secreted in the placenta include: nerve growth factor, fibroblast, transforming growth factor, platelet-derived growth factor. Inhibin and activin are produced in the placenta. Inhibin is determined in the syncytiotrophoblast, and its synthesis is stimulated by placental prostaglandins E and F2ffa.

The action of placental inhibin and activin is similar to the action of ovarian ones. They take part in the production of GnRH, hCG and steroids: activin stimulates, and inhibin inhibits their production.

Placental and decidual activin and inhibin appear in early pregnancy and appear to be involved in embryogenesis and local immune responses.

Among pregnancy proteins, the most famous is SP1 or beta1-glycoprotein or trophoblast-specific beta1-glycoprotein (TBG), which was discovered by Yu.S. Tatarinov. in 1971. This protein increases during pregnancy like placental lactogen and reflects the functional activity of the trophoblast.

Eosinophilic basic protein pMBP - its biological role is not clear, but by analogy with the properties of this protein in eosinophils, it is assumed that it has a detoxifying and antimicrobial effect. It has been suggested that this protein influences the contractility of the uterus.

Soluble placental proteins include a group of proteins with different molecular weights and biochemical composition of amino acids, but with common properties - they are found in the placenta, in the placental-fetal bloodstream, but are not secreted into the mother’s blood. There are now 30 of them discovered, and their role is mainly limited to ensuring the transport of substances to the fetus. The biological role of these proteins is being intensively studied.

In the mother-placenta-fetus system, ensuring the rheological properties of blood is of great importance. Despite the large contact surface and slower blood flow in the intervillous space, the blood does not thrombose. This is prevented by a complex complex of coagulating and anticoagulant agents. The main role is played by thromboxane (TXA2, secreted by the mother's platelets - an activator of maternal blood coagulation, as well as receptors for thrombin on the apical membranes of the syncytiotrophoblast, which promote the conversion of maternal fibrinogen into fibrin. In contrast to the coagulation factors, the anticoagulation system operates, including annexations V on the surface of the microvilli of the syncytiotrophoblast, on the border of maternal blood and villous epithelium; prostacyclin and some prostaglandins (PG12 and PGE2), which, in addition to vasodilation, have an antiplatelet effect. A number of factors with antiplatelet properties have also been identified, and their role remains to be studied.

Types of placentas

Marginal attachment - the umbilical cord is attached to the placenta from the side. Meningeal attachment (1%) - umbilical vessels pass through syncytio-capillary membranes before attaching to the placenta. When such vessels rupture (as is the case with the vessels of the placenta previa), blood loss occurs from the fetal circulatory system. Accessory placenta (placenta succenturia)(5%) are additional lobules lying separately from the main placenta. If an additional lobule is retained in the uterus in the postpartum period, bleeding or sepsis may develop.

Membranous placenta (placenta membranacea)(1/3000) is a thin-walled sac that surrounds the fetus and thereby occupies most of the uterine cavity. Located in the lower segment of the uterus, such a placenta predisposes to bleeding in the prenatal period. It may not separate during the fetal period. Placenta accreta (placenta accreta)- abnormal accretion of all or part of the placenta to the wall of the uterus.

Placenta previa (placenta praevia)

The placenta lies in the lower segment of the uterus. Placenta previa is associated with conditions such as large placenta (eg, twins); uterine anomalies and fibroids; damage to the uterus (multiple births, recent surgery, including caesarean section). Starting at 18 weeks, ultrasound allows visualization of low-lying placentas; most of them move to their normal position by the beginning of labor.

In type I, the edge of the placenta does not reach the internal uterine os; in type II, it reaches but does not close the internal uterine os from the inside; in type III, the internal uterine os is closed from the inside by the placenta only when the cervix is ​​closed, but not when the cervix is ​​dilated. In type IV, the internal uterine os is completely closed from the inside by the placenta. The clinical manifestation of an abnormal location of the placenta may be bleeding in the prenatal period (antepartum). Overextension of the placenta, when the overextended lower segment is a source of bleeding, or the inability of the fetal head to insert (with a high location of the presenting part). The main problems in such cases are related to bleeding and the method of delivery, since the placenta causes obstruction of the uterine ostium and can be removed during labor or become attached (in 5% of cases), especially after a previous cesarean section (more than 24% of cases).

Tests to assess placental function

The placenta produces progesterone, human chorionic gonadotropin, and human placental lactogen; only the latter hormone can provide information about the well-being of the placenta. If at a gestational age of more than 30 weeks, upon repeated determination, its concentration is below 4 μg/ml, this suggests a violation of placental function. The well-being of the fetal/placental axis is monitored by measuring the daily excretion of total estrogens or urinary estriol or by measuring estriol in the blood plasma, since pregnenolone synthesized by the placenta is subsequently metabolized by the fetal adrenal glands and liver, and then again by the placenta to synthesize estriol. Estradiol levels in urine and plasma will be low if the mother suffers from severe liver damage or intrahepatic cholestasis or is taking antibiotics; if the mother has impaired renal function, there will be a low level of estradiol in the urine and an increased level in the blood.

During pregnancy, the placenta is the most important organ that is responsible for providing the fetus with all the necessary elements and also protects it from harmful substances. It is unique in that it exists only during pregnancy and disappears after birth.

Definition of placenta

The name of this organ literally translates from Latin as “cake”. It received this designation because of its shape. The placenta is also called the “baby place”. It is considered the first home of the future baby, where he is isolated from the negative influence of the environment. It is this protection that is the main role assigned to the placenta.

The organ consists of blood vessels of the mother and baby, which are connected in a certain way. In this case, a distinction is made between the fetal part and the maternal part, which are separated from each other by a thin partition - the placental barrier, which plays the role of a filter. It does not create obstacles to the embryo’s access to oxygen and other important microelements, but it also does not allow harmful substances to have a negative impact on the baby.

During pregnancy, the placenta also ensures that the baby's waste products are released back into the mother's blood. Next, they enter the woman’s kidneys for subsequent processing. It is surprising that the blood of mother and baby in the placental vessels is never mixed during the entire pregnancy.

Main functions

The role of the placenta in the proper formation of the child is enormous. It performs a number of vital functions:

• transports oxygen, which is in the mother’s blood, to the embryo;
• supplies the child with substances that ensure his harmonious development and removes decay products;
• creates a barrier that protects against viruses and infections;
• participates in the formation of the baby’s immunity;
• synthesizes estrogens, progesterone, hCG and other hormones important for the development of the child.

Considering how significant the role of the placenta is, doctors closely monitor its development throughout pregnancy so that if any pathology is detected, they can immediately take measures to preserve the fetus.

Terms of education and development

When does its formation begin? Immediately after the first minutes, after fertilization has occurred, the creation of the placenta occurs. It is formed after the division of the egg. Along with the cells that ensure the birth of a new life, others are also formed - those responsible for the contact of the embryo with the maternal body.

10 days after fertilization has occurred, a lacuna with the mother’s blood vessels forms inside the uterus. It is there, surrounded by the shell, that the baby is located. His own vessels are also introduced there. Thus, a placenta appears, changing throughout pregnancy as the child’s needs increase. By week 13, its structure is fully determined. She begins to carry out almost all the work to ensure the life of the unborn baby.

The placenta becomes fully formed at 18 weeks. It is at this time that the full functioning of the fetoplacental complex begins, which, in addition to the organ we are discussing, includes the umbilical cord and fetal membrane.

It is considered normal when the location of the placenta is the anterior or posterior uterine wall, but sometimes it can be located near its base. An excessively low position is considered a pathology and causes risks of miscarriage and complications during childbirth.

The exact timing of maturation depends on the individual characteristics of the organism, but in most cases maximum maturity occurs at 36 weeks. Before birth, its thickness ranges from 2 to 4 cm, and its diameter can reach up to 18 cm.

After the child is born, the functioning of the placenta ends, it leaves the body, independently separating from the uterine walls. As a rule, this process takes no more than 20 minutes after birth, but there are cases when the separation time can reach an hour. At this moment, the doctor is required to carefully examine its integrity to make sure that there are no parts left in the woman’s body that can cause inflammation.

Possible problems at work

During pregnancy, the placenta does not always develop perfectly. There are pathologies that can harm both mother and child. Most often, organ detachment or improper attachment to the uterus occurs. In addition, there are disturbances in maturation, size, thickness, and lobulation. Serious pathologies also include:

• placental infarction;
• formation of intraplacental blood clots;
• the occurrence of infectious inflammation, which is called placentitis;
• formation and development of various tumors and hyperechoic inclusions (calcifications).

Any deviation from the norm requires the attention of specialists and the adoption of measures to ensure the further proper course of pregnancy.

How to avoid developmental disabilities?

There are many reasons for the occurrence of various pathologies of the placenta. They are caused by hormonal imbalances, anemia and severe gestosis, Rh conflict, maternal infections and chronic diseases, congenital malformations of the embryo.

The following factors also affect the placenta:

• consumption of alcoholic beverages and cigarettes by the mother;
• stress;
• overweight or underweight mother and many other reasons.

It should be borne in mind that problems with the formation and development of a child's place can cause irreparable harm to the health of the unborn baby. It is extremely important for a woman to carefully monitor her well-being during gestation. Both physical and psychological health matter. During pregnancy, it is necessary to reduce the level of stress and unnecessary stress, give up bad habits and monitor your diet.

In order to take timely measures, you should know the signs of abnormalities in the formation of the placenta. These are pain in the lower abdomen, bleeding, shortness of breath, decreased blood pressure and increased temperature. However, there are often times when only a specialist can see the problem. Therefore, it is very important to do all routine examinations and be attentive to your health, on which the life of the unborn baby depends.