Today, many mothers know far more about pregnancy than our parents knew. Therefore, many women during pregnancy worry about the state of their health, and are very worried if the doctor talks about the condition of such an important organ during pregnancy as the placenta. This organ performs the most important functions, and without it it is impossible to carry a pregnancy to term.
Deviations in the structure or functioning of the placenta can lead to complications for the mother or fetus, and certain measures must be taken in a timely manner to correct everything. But what can happen to the placenta, and how can it be dangerous? Let's figure it out together.
What is the placenta?
The term “placenta” itself comes from the Greek language and is translated by the simple word “cake”. Indeed, in appearance, the placenta resembles a large and voluminous cake with a “tail” extending from it in the form of an umbilical cord. But this cake is extremely important for every woman carrying a baby; it is due to the existence of the placenta that it is possible to carry and give birth to a child normally.
In terms of structure, the placenta, or, as it may be called differently in the literature, “baby place,” is a complex organ. The beginning of its formation occurs at the time of implantation of the embryo into the wall of the uterus (from the moment the embryo attaches to one of the walls of the uterus).
How does the placenta work?
The main part of the placenta is special villi, which branch in it and form from the beginning of pregnancy, resembling the branches of centuries-old trees. The baby’s blood circulates inside the villi, and outside the villi are actively washed by the blood coming from the mother. That is, the placenta combines two circulatory systems at once - the maternal one from the uterus, and the fetal one from the amniotic membranes and the baby. According to this, the sides of the placenta are also different - smooth, covered with membranes, with an emerging umbilical cord - on the fetal side, and uneven lobulated - on the mother's side.
What is the placental barrier?
It is in the area of the villi that an active and constant exchange of substances occurs between the baby and his mother. From the mother's blood, the fetus receives oxygen and all the necessary nutrients for growth and development, and the baby gives the mother metabolic products and carbon dioxide, which the mother removes from the body for two. And the most important thing is that the blood of the mother and fetus does not mix in any part of the placenta. The two vascular systems - the fetus and the mother - are separated by a unique membrane that is capable of selectively allowing some substances to pass through and retaining other, harmful substances. This membrane is called the placental barrier.
Gradually forming and developing along with the fetus, the placenta begins to fully function by approximately twelve weeks of pregnancy. The placenta retains bacteria and viruses penetrating into the maternal blood, special maternal antibodies that can be produced in the presence of Rh conflict, but at the same time the placenta easily allows the nutrients and oxygen necessary for the child to pass through. The placental barrier has the property of special selectivity; different substances coming from different sides of the placental barrier penetrate the membrane to varying degrees. Thus, many minerals actively penetrate from the mother to the fetus, but practically do not penetrate from the fetus to the mother. And also, many toxic substances actively penetrate from the baby to the mother, but practically do not pass back from her.
Hormonal function of the placenta
In addition to the excretory function, fetal breathing (since the placenta temporarily replaces the baby's lungs), and many other functions, the placenta has another function that is important for pregnancy as a whole - hormonal. Once the placenta begins to fully function, it can produce up to 15 different hormones that perform various functions during pregnancy. The very first of these are sexual functions, which help in maintaining and prolonging pregnancy. Therefore, gynecologists, if there is a threat of early pregnancy termination, always wait 12-14 weeks, helping in the early weeks of pregnancy with external hormones (duphaston or utrozhestan). Then the placenta begins to actively work and the threat disappears.
The functions of the placenta are so great that in the initial stages the placenta grows and develops even faster than your baby grows. And this is not without reason, by the time of 12 weeks the fetus weighs about 5 grams, and the placenta is up to 30 grams, by the end of pregnancy, at the time of birth, the size of the placenta will be about 15-18 cm, and the thickness will be up to 3 cm, with a weight of about 500 -600 grams.
Umbilical cord
The placenta on the fetal side is connected to the baby by a special strong cord - the umbilical cord, inside which there are two arteries and one vein. The umbilical cord can attach to the placenta in several ways. The first and most common is the central umbilical cord attachment, but lateral or marginal umbilical cord attachment may also occur. The umbilical cord functions are not affected in any way by the method of attachment. A very rare option for attaching the umbilical cord may be attachment not to the placenta itself, but to its fetal membranes, and this type of attachment is called membrane.
Problems with the placenta
Most often, the placenta and umbilical cord system work harmoniously and supply the baby with oxygen and nutrition. But sometimes malfunctions may occur in the placenta due to the influence of various factors - external or internal. There are various kinds of developmental disorders or problems with the functioning of the placenta. Such changes in the placenta do not go unnoticed for the mother and fetus; often problems with the placenta can have serious consequences. We will talk about the main abnormalities in the development and functioning of the placenta and how to identify and treat them.
Placental hypoplasia
Reducing the size or thinning of the placenta in medical language is called “placental hypoplasia.” You should not be afraid of this diagnosis, because... it occurs quite often. The fetus is affected only by a significant decrease in the diameter and thickness of the placenta.
A significantly reduced placenta, a small baby's place, is uncommon. This diagnosis is made if the reduction in size is significant compared to the lower limit of normal for the size of the placenta at a given stage of pregnancy. The causes of this type of pathology have not yet been clarified, but according to statistics, usually a small placenta is associated with the development of severe genetic abnormalities in the fetus.
I would like to immediately make a reservation that the diagnosis of “placental hypoplasia” is not made based on a single ultrasound; it can only be made as a result of long-term observation of a pregnant woman. In addition, it is always worth remembering that there may be individual deviations in the size of the placenta from standard, generally accepted normal values, which will not be considered a pathology for each specific pregnant woman in each of her pregnancies. So, for a small and slender woman, the placenta should be smaller in size than for a large and tall woman. In addition, there is no absolute proof of the relationship between placental hypoplasia and the presence of genetic disorders in the fetus. But when a diagnosis of placental hypoplasia is made, parents will be advised to undergo medical genetic counseling.
During pregnancy, a secondary reduction in size of the placenta may occur, which may be associated with exposure to various unfavorable factors during pregnancy. This could be chronic stress or fasting, drinking alcohol or smoking, or drug addiction. Also, the causes of underdevelopment of the placenta during pregnancy can be hypertension in the mother, a sharp exacerbation of chronic pathology, or the development of some acute infections during pregnancy. But in the first place when the placenta is underdeveloped, there is gestosis with the development of severe edema, high blood pressure and the appearance of protein in the urine.
Changes in the thickness of the placenta occur. A placenta is considered thin if it has insufficient mass but is of a size that is quite normal for its age. Often, such thin placentas occur with congenital defects of the fetus, and children are born with manifestations, which causes serious problems with the health of the newborn. But unlike a primary hypoplastic placenta, such children are not associated with the risk of developing dementia.
Sometimes a membranous placenta is formed - it is very wide and very thin, measuring up to 40 cm in diameter, almost twice as large as normal. Typically, the cause of the development of such a problem is a chronic inflammatory process in the endometrium, which leads to dystrophy (depletion) of the endometrium.
Placental hyperplasia
In contrast, a very large, giant placenta occurs, which usually occurs in cases of severe gestational diabetes. Enlargement (hyperplasia) of the placenta also occurs in diseases of pregnant women such as toxoplasmosis or syphilis, but this is not common. An increase in the size of the placenta may be the result of kidney pathology in the unborn baby, if present, when the fetal red blood cells with Rh protein begin to attack the mother's antibodies. The placenta can increase significantly in case of thrombosis of its vessels, if one of the vessels is blocked, as well as in case of pathological growth of small vessels inside the villi.
An increase in the thickness of the placenta more than normal may be associated with its premature aging. Thickening of the placenta is also caused by such pathologies as Rh-conflict, hydrops fetalis, diabetes mellitus in pregnancy, gestosis, viral or infectious diseases suffered during pregnancy, placental abruption. Thickening of the placenta is normal in multiple pregnancies.
In the first and second trimesters, an enlarged placenta usually indicates a previous viral disease (or latent carriage of the virus). In this case, the placenta grows to prevent disease in the fetus.
Rapid growth of the placenta leads to its premature maturation, and consequently, aging. The structure of the placenta becomes lobular, calcifications form on its surface, and the placenta gradually ceases to provide the fetus with the necessary amount of oxygen and nutrients. The hormonal function of the placenta also suffers, which leads to premature birth.
Treatment for placental hyperplasia usually involves careful monitoring of the fetus.
What is dangerous about changing the size of the placenta?
Why are doctors so worried about significant changes in placenta size? Usually, if the size of the placenta changes, functional insufficiency in the functioning of the placenta may also develop, that is, so-called feto-placental insufficiency (FPI), problems with the supply of oxygen and nutrition to the fetus, will form. The presence of FPN may mean that the placenta cannot fully cope with the tasks assigned to it, and the child experiences a chronic lack of oxygen and the supply of nutrients for growth. In this case, problems can grow like a snowball, the child’s body will suffer from a lack of nutrients, as a result, it will begin to lag behind in development and IUGR (intrauterine growth retardation in the fetus) or fetal growth restriction syndrome (FGR) will form.
To prevent this from happening, it is best to engage in advance prevention of such conditions, treatment of chronic pathology even before pregnancy, so that exacerbations do not occur during pregnancy. During pregnancy, it is important to control blood pressure, blood glucose levels and protect the pregnant woman as much as possible from any infectious diseases. You also need a good diet with enough proteins and vitamins.
When diagnosing “placental hypoplasia” or “placental hyperplasia”, careful monitoring of the course of pregnancy and the condition of the fetus is first required. The placenta cannot be cured or corrected, but there are a number of medications prescribed by a doctor to help the placenta perform its functions.
In the treatment of emerging feto-placental insufficiency, special drugs are used - Trental, Actovegin or Curantil, which can improve blood circulation in the placental system on both the maternal and fetal sides. In addition to these medications, intravenous infusions of drugs can be prescribed - rheopolyglucin with glucose and ascorbic acid, saline solutions. The development of FPN can have varying degrees of severity and should not be self-medicated; this can lead to the loss of the child. Therefore, it is necessary to follow all the appointments of the obstetrician-gynecologist.
Changes in the structure of the placenta
The normal placenta has a lobular structure; it is divided into approximately 15-20 lobules of equal size and volume. Each of the lobules is formed from villi and a special tissue that is located between them, and the lobules themselves are separated from each other by partitions, however, not complete ones. If changes occur in the formation of the placenta, new variants of the structure of the lobules may arise. Thus, the placenta can be bilobed, consisting of two equal parts that are connected to each other by special placental tissue; a double or triple placenta can also be formed, the umbilical cord will be attached to one of the parts. Also, a small additional lobule may be formed in a normal placenta. Even less commonly, a so-called “fenestrated” placenta may occur, which has areas covered with a membrane and resembling windows.
There can be many reasons for such deviations in the structure of the placenta. Most often this is a genetically determined structure, or a consequence of problems with the uterine mucosa. Prevention of such problems with the placenta can be the active treatment of inflammatory processes in the uterine cavity even before pregnancy, during the planning period. Although deviations in the structure of the placenta do not have such a strong effect on the child during pregnancy, and almost never affect its development. But during childbirth, such a placenta can cause a lot of trouble for doctors - such a placenta can be very difficult to separate from the wall of the uterus after the baby is born. In some cases, separation of the placenta requires manual control of the uterus under anesthesia. Treatment for the abnormal structure of the placenta during pregnancy is not required, but during childbirth you must remind the doctor about this so that all parts of the placenta are born and no pieces of the placenta remain in the uterus. This is dangerous due to bleeding and infection.
Degree of maturity of the placenta
During its existence, the placenta goes through four successive stages of maturation:
Degree of placenta maturity 0- normally lasts up to 27-30 weeks. Sometimes at these stages of pregnancy there is 1 degree of placental maturity, which can be caused by smoking or drinking alcohol during pregnancy, as well as by previous infection.
Degree of placenta maturity 1- from 30 to 34 weeks of pregnancy. During this period, the placenta stops growing and its tissues thicken. This is a crucial period when any deviations can pose a danger to the health of the fetus.
Degree of placenta maturity 2- lasts from 34 to 39 weeks of pregnancy. This is a stable period when some advance in the maturity of the placenta should not cause concern.
Degree of placenta maturity 3- can normally be diagnosed starting from the 37th week of pregnancy. This is a stage of natural aging of the placenta, but if it is combined with fetal hypoxia, the doctor may recommend a cesarean section.
Disturbances in placental maturation
For each stage of placenta formation, there are normal periods in weeks of pregnancy. Too fast or slow passage of certain stages by the placenta is a deviation. The process of premature (accelerated) maturation of the placenta can be uniform or uneven. Typically, expectant mothers with underweight experience uniform premature aging of the placenta. Therefore, it is important to remember that pregnancy is not the time to follow various diets, since their consequences can be premature birth and the birth of a weak baby. The placenta will mature unevenly if there are problems with blood circulation in some of its zones. Typically, such complications occur in overweight women with prolonged late toxicosis of pregnancy. Uneven maturation of the placenta occurs more often with repeated pregnancies.
Treatment, as with feto-placental insufficiency, is aimed at improving blood circulation and metabolism in the placenta. To prevent premature aging of the placenta, it is necessary to take measures to prevent pathologies and gestosis.
But delays in the maturation of the placenta occur much less frequently, and the most common reasons for this may be the presence of diabetes mellitus in the pregnant woman, alcohol consumption and smoking. Therefore, it is worth giving up bad habits while carrying a baby.
Placental calcifications
The normal placenta has a spongy structure, but by the end of pregnancy some of its areas may become stone; such areas are called petrificates or placental calcifications. Hardened areas of the placenta are not able to perform their functions, but usually the remaining parts of the placenta do an excellent job with the task assigned to them. As a rule, calcifications occur due to premature aging of the placenta or postterm pregnancy. In such cases, the doctor will closely monitor the pregnant woman to exclude the development of fetal hypoxia. But usually such a placenta functions quite normally.
Low attachment and placenta previa
Ideally, the placenta should be located in the upper part of the uterus. But there are a number of factors that prevent the normal location of the placenta in the uterine cavity. These could be uterine fibroids, tumors of the uterine wall, malformations, multiple pregnancies in the past, inflammatory processes in the uterus, or abortions.
Requires more careful observation. It usually tends to rise during pregnancy. In this case, there will be no obstacles to natural childbirth. But it happens that the edge of the placenta, part of it, or the entire placenta blocks the internal os of the uterus. If the placenta partially or completely covers the cervix of the uterus, natural childbirth is impossible. Typically, if the placenta is abnormally located, a caesarean section is performed. Such abnormal positions of the placenta are called incomplete and complete placenta previa.
During pregnancy, a woman may experience bleeding from the genital tract, which leads to anemia and fetal hypoxia. The most dangerous is partial or complete placental abruption, which leads to the death of the fetus and a threat to the life of the mother. , including sexual, you cannot exercise, swim in the pool, walk a lot and work.
What is placental abruption?
What is premature placental abruption? This is a condition when the placenta (normally or abnormally located) leaves its place of attachment before its due date, that is. In case of placental abruption, an emergency cesarean section is necessary to save the life of the mother and fetus. If the placenta has separated in small areas, then doctors try to stop this process, maintaining the pregnancy. But even with minor placental abruption and slight bleeding, the risk of repeated episodes of abruption remains until childbirth, and the woman is carefully monitored.
The causes of placental abruption can be injuries or blows to the abdomen, the presence of chronic pathologies in a woman, which leads to problems with blood circulation, defects in the formation of the placenta. Premature placental abruption can be caused by complications during pregnancy - most often gestosis with increased pressure, protein in the urine and edema, which affects all organs and systems of the mother and fetus. It is important to remember that premature placental abruption is the most dangerous complication of pregnancy!
Placental abruption
Rice. 1 - complete placenta previa;
Rice. 2 - marginal placenta previa;
Rice. 3 - partial placenta previa
1 - cervical canal; 2 - placenta; 3 - umbilical cord; 4 - amniotic sac
Dense attachment and placenta accreta
Sometimes anomalies occur not only in the location, but also in the method of attachment of the placenta to the wall of the uterus. A very dangerous and serious pathology is placenta accreta, in which the placental villi are attached not only to the endometrium (the inner layer of the uterus, which peels off during childbirth), but also grow deep into the tissues of the uterus, into its muscular layer.
There are three degrees of severity of placenta accreta, depending on the depth of villous germination. In the most severe, third degree, villi grow into the uterus to its full thickness and can even lead to uterine rupture. The cause of placenta accreta is the inferiority of the endometrium due to congenital defects of the uterus or acquired problems.
The main risk factors for placenta accreta are frequent abortions, cesarean sections, fibroids, as well as intrauterine infections and uterine malformations. Low placentation may also play a certain role, since in the area of the lower segments the growth of villi into the deeper layers of the uterus is more likely.
With true placenta accreta, in the vast majority of cases, removal of the uterus with placenta accreta is required.
An easier case is the dense attachment of the placenta, from the accreta, differing in the depth of penetration of the villi. Tight attachment occurs when the placenta is low or previa. The main difficulty with such attachment of the placenta is the delay in its birth or the complete impossibility of spontaneous passage of the placenta in the third stage of labor. If the attachment is tight, they resort to manual separation of the placenta under anesthesia.
Diseases of the placenta
The placenta, like any organ, can hurt. It can become infected, infarctions (areas deprived of blood circulation) can develop in it, blood clots can form inside the vessels of the placenta, and the placenta itself can even undergo tumor degeneration. But this, fortunately, does not happen often.
Infectious damage to placental tissue (placentitis) is caused by various microbes that can penetrate the placenta in various ways. So, they can be brought with the bloodstream, penetrate from the fallopian tubes, ascending from the vagina, or from the uterine cavity. The inflammation process can be spread throughout the entire thickness of the placenta or occur in its individual areas. In this case, treatment must be specific, and it depends on the type of pathogen. Of all the possible drugs, the one that is acceptable for pregnant women at this stage will be selected. And for the purpose of prevention before pregnancy, it is necessary to carry out comprehensive therapy for chronic infections, especially in the genital tract.
Placental infarction usually develops, like any other, as a result of prolonged ischemia (spasm of placental vessels), and then the areas of the placenta that receive blood from these vessels die as a result of oxygen deficiency. Typically, infarctions in the placenta occur as a result of severe gestosis or the development of hypertension in the pregnant woman. Placentitis and placental infarction can cause FPN and problems with fetal development.
Sometimes, as a result of inflammation or damage to the vascular wall, when blood viscosity is disrupted, or due to sudden movements of the fetus, blood clots form inside the placenta. But small blood clots do not affect the course of pregnancy in any way.
A modern married couple expecting a happy addition is significantly different from their parents. At the service of young people there are a dozen special magazines for pregnant women, the same number of websites on the Internet, courses of various kinds, consultations with doctors... Yes, our contemporary is an advanced user in this field, and you cannot intimidate him with Latin. But, as the ancients said: “In much wisdom there is much sorrow!” It's no secret what an important role the placenta plays during pregnancy. And of course, we get scared when doctors tell us about various abnormalities associated with it. We fear for a successful outcome of the pregnancy, we worry about the baby. And we don’t always know exactly what to do.
Today we will talk about everything that literate parents need to know on this topic. The word “placenta” itself is of Greek origin and translated means “cake”. This prosaic and, in general, irreverent name is given to the placenta for its appearance. Indeed, in appearance it very much resembles a thick and round cake. But you and I know how deceiving appearances can be!
What is placenta
The structure of the placenta, or, as it is also called, the baby's place, is very complex. It begins to form almost from the moment the embryo attaches to the wall of the uterus, or, as doctors say, from the moment of implantation. The main part of the placenta is represented by villi, which branch in it, creating a resemblance to the crown of a mighty ancient oak. The baby's blood flows inside the villi; outside they are washed with their mother's blood. Thus, it becomes clear that there are two systems of blood vessels in the placenta - fetal and maternal, and it is here that constant exchange of substances occurs between mother and child. Oxygen and nutrients come from the mother’s blood, the baby “returns” carbon dioxide and metabolic products that must be eliminated from the body. And, what is especially interesting, the blood of mother and child does not mix anywhere! The fact is that the two vascular systems are separated by an amazing membrane that can allow some substances to pass through and prevent the penetration of others. It is called the “placental barrier”.
The placental barrier begins to work fully to protect the fetus by 12 weeks. It retains bacteria contained in the mother’s blood, some viruses, and the mother’s antibodies produced during Rhesus conflict, but freely allows oxygen and nutrients to pass through. It is known about the barrier function of the placenta during pregnancy that it is very selective. The same substances overcome this threshold in different ways towards the fetus and towards the mother. For example, fluoride passes perfectly through the barrier from mother to baby, but does not pass at all in the opposite direction. Or bromine: this trace element penetrates to the baby much faster than back.
In addition to protective, excretory, respiratory (after all, it replaces the baby’s lungs!) and other described functions, the placenta has another, no less important – hormonal. Imagine, the placenta produces about 15 hormones for various purposes! And among them, the first place is occupied by sex hormones, designed to maintain pregnancy.
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The role of the placenta during pregnancy is so great that at first it even grows faster than the baby. Indeed, at 12 weeks the fetus weighs 4 g, and the placenta weighs up to 30 g. At the end of pregnancy, closer to the time of birth, the diameter of the placenta will be about 15-18 cm, thickness - 2-3 cm, weight - 500-600 g.
The placenta is connected to the baby by the umbilical cord, which contains blood vessels (two arteries and a vein). The umbilical cord, or umbilical cord, can attach to the placenta in three different ways. The first and most common is the central attachment; Lateral and marginal attachment is less common. And very rarely the umbilical cord is attached not to the placenta itself, but to the fetal membranes. This type of attachment is called shell.
Unfortunately, things don't always work out the way we would like. Any system, even the most well-coordinated one, sometimes fails. For a variety of reasons, at different stages of pregnancy, deviations in the development and functioning of the placenta occur. These changes never go unnoticed for mother and baby, and often have dire consequences. Therefore, all parents need to know the causes and manifestations of placental abnormalities. We will tell you about the most common problems that obstetricians and gynecologists have to face today, and about methods of prevention and treatment of placental pathology.
Placenta during pregnancy
Hypoplasia of the placenta, or initially small placenta, is uncommon. By saying “small placenta,” we mean a significant reduction in its size relative to the lower limit of the norm expected for a given stage of pregnancy. The exact origin of this pathology is unknown, but the combination of primary placental hypoplasia with genetic pathology of the fetus has been statistically proven.
It’s worth mentioning right away: such a diagnosis can only be made after long-term observation. That is, ultrasound examination alone is not enough for such serious conclusions. And of course, we must not forget that there are individual deviations from generally accepted norms, which will not be a pathology for a given woman and a particular pregnancy. A small, graceful mother will have a much more delicate placenta. Finally, we are not talking about a 100% combination of placental hypoplasia during pregnancy and genetic disorders. If the diagnosis is confirmed, parents should undergo a medical genetic examination.
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During pregnancy, a secondary reduction in the size of the placenta is possible, associated with various unfavorable factors. These are stress, malnutrition, smoking, alcoholism, drug addiction of the mother. Often the cause of secondary placental hypoplasia is hypertension in a pregnant woman, exacerbation of chronic diseases, or an acute infection during pregnancy. However, gestosis in pregnant women remains in first place, manifested by edema, increased blood pressure and the appearance of protein in the urine.
A giant or very large placenta during pregnancy most often develops with severe diabetes mellitus. There is also a sharp increase in the size of a child's place when a pregnant woman becomes ill with infectious diseases such as syphilis or toxoplasmosis. Finally, a giant placenta may be a manifestation of the baby’s kidney pathology, Rh conflict - a situation in which the red blood cells of a Rh-positive fetus are destroyed by antibodies produced in the body of a Rh-negative mother. A significant increase in the size of the placenta is observed with thrombosis of its vessels, when the lumen of the vessel is closed by a thrombus, or with pathological proliferation of small vessels in the villi.
Sometimes there is a membranous placenta - extensive and thin. Such a child's place has 30-40 cm in diameter (normally its size is 18-20 cm), and its thickness is sharply reduced. The reason for the development of this anomaly is a chronic inflammatory process in the uterus, leading to thinning (dystrophy) of its mucous membrane - the endometrium.
What are the dangers of a significant change in the size of the placenta during pregnancy? In this case, functional insufficiency of the placenta often develops, the same fetoplacental insufficiency - FPI, which many readers have already heard about. This means that the placenta does not cope with its tasks properly and the baby is chronically lacking oxygen and nutrients. The problem grows like a snowball: the child’s body, suffering from a deficiency of necessary substances, begins to lag behind in development - intrauterine growth retardation is formed (abbreviated as IUGR or FGR - fetal growth retardation syndrome).
It is clear that prevention in this case is the treatment of chronic diseases, and it is better - in advance, before pregnancy. In this case, special attention should be paid to diseases of the uterus and appendages. It is also necessary to correct blood pressure and blood sugar levels, protect the pregnant woman as much as possible from the risk of infection (clinics, hospitals, public transport, child care facilities, etc.), a complete rational and balanced diet, and mandatory intake of multivitamin complexes for pregnant women.
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To treat fetoplacental insufficiency, drugs such as ACTOVEGIN, KURANTIL, TRENTAL are used. These medications can improve blood circulation in the mother-placenta-fetus system. In addition to the main drugs, in case of delayed fetal development, intravenous administration of rheopolyglucin, glucose, ascorbic acid, and saline solutions is prescribed. Like any pathology, both FPN and IUGR have varying degrees of severity; The treatment tactics depend on this. In any case, it is strictly forbidden to self-medicate. Both the pathology and the drugs used are quite serious, so strictly follow your doctor’s instructions!
Structure of the placenta
Normally, the placenta has a lobular structure. The whole of it is divided into 15-20 lobules, each of which is formed from villi and tissue located between the villi; the lobules are separated from each other by incomplete partitions.
With changes in the formation of the placenta during pregnancy, new variants of the lobular structure arise. Thus, there is a bilobed placenta, which consists of two lobes connected by placental tissue. Sometimes a double or triple placenta is formed. It is represented by two or three equal parts, respectively, to one of which the umbilical cord goes. A normally formed placenta may develop a separately located additional lobe. Less commonly, a definitive placenta is found that has membrane-covered areas resembling windows.
The causes of changes in the structure of the placenta during pregnancy are very diverse. Most often, the structural disorder is caused genetically or is a consequence of inflammation of the uterine mucosa; Accordingly, prevention will also include serious treatment of inflammatory diseases of the genital area before a planned pregnancy. It must be said that structural deviations have a lesser effect on the baby during pregnancy, but they can cause a lot of problems and troubles during childbirth and the postpartum period - such a placenta may have difficulty separating from the wall of the uterus after the baby is born, which will require a manual examination of the uterus. Therefore, changes in the structure of the placenta do not require treatment during pregnancy, but require increased attention from the doctor during the birth of the placenta and especially in the early postpartum period. If, based on the results of the ultrasound, you know about the pathology of the structure of the placenta, be sure to warn the doctor delivering the baby about this!
Maturation of the placenta
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During its existence, the placenta sequentially goes through 4 stages of development during pregnancy: formation, growth, maturity and aging. Nature has its own time limit for each stage. If the normal course of pregnancy is disrupted, the maturation of the placenta may be too rapid or delayed.
Premature or accelerated ripening is of two types: uniform and uneven. Underweight mothers “sin” by uniformly accelerating the maturation of the placenta, so remember, “thin and loud,” pregnancy is not the time for dieting! The consequence may be premature birth.
Uneven maturation of the placenta occurs when blood circulation is impaired in certain areas of the placenta. This complication occurs in obese pregnant women, with long-term late toxicosis, and more often with repeated pregnancy. This increases the risk of miscarriages, stillbirths and premature births. Treatment is similar to that for FPP, prevention – prevention and correction of late toxicosis. Delayed placental maturation is observed much less frequently. The most common causes are maternal diabetes, smoking and alcoholism. The last two reasons probably don't need any comment!
Diseases of the placenta
Alas, the placenta gets sick during pregnancy, just like us! It is susceptible to infection, heart attacks, when areas deprived of blood supply arise; Blood clots may form in the vessels of the placenta, and the placenta may even undergo tumor degeneration. Fortunately, this doesn't happen often. Still, let’s touch on this problem.
Placentitis, or an infection of the placenta, is caused by various microorganisms that try to get into the placenta in all imaginable ways. They can be carried by the bloodstream, penetrate the fallopian tubes from the appendages, and “rise” from the vagina. And of course, if the microbe already constantly lives in the uterine cavity, it will not be difficult for it to penetrate the placenta!
Inflammation can spread to the entire placenta or to its individual components. Of course, here too the severity of the disease is distinguished. Treatment will be specific, depending on the type of pathogen; Of course, from the possible medications, your doctor will choose those that are approved for pregnant women. As for prevention, you probably already understand: it is necessary to treat a chronic infection, primarily of the genital tract!
Placental infarction, like myocardial infarction, develops as a result of prolonged vascular spasm; the area of placental tissue that was supplied with blood by this vessel experiences ischemia - an acute lack of oxygen - and dies. Infarction of placental tissue is usually a consequence of severe late toxicosis or hypertension in a pregnant woman, so prevention will be appropriate. Both of these complications can cause placental insufficiency and developmental delays in the baby.
Intraplacental blood clots occur in the vessels of the placenta as a result of inflammation, damage to the vessel wall, impaired blood viscosity during toxicosis or, simply, when the baby moves. Nothing is known about the direct effect of blood clots on the course of pregnancy and the development of the child.
As for placental tumors during pregnancy, I would not like to dwell on them in detail. Note that they can be benign and malignant, are often accompanied by polyhydramnios, malformations of the fetus, interfere with its size and “steal” nutrients from it.
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Location of the placenta
Ideally, the baby's place is located in the upper parts of the uterus. However, there are conditions and diseases that prevent the usual location of the placenta during pregnancy. Such ailments include uterine fibroids (benign tumors of muscle tissue), congenital malformations of the uterus, a large number of pregnancies in the mother’s past, and most importantly, abortions and inflammatory processes in the uterus.
Located on the “lower floor,” the placenta can edge, part, or completely cover the exit from the uterine cavity—the internal os. With the last option of location, independent physiological childbirth is definitely impossible, with the previous two – it is called into question; In most cases, a caesarean section is performed. Abnormal position of the placenta is called previa and is often manifested by repeated bleeding from the genital tract. The consequences of bleeding can be significant anemia (decreased hemoglobin in the blood), oxygen starvation of the baby, partial and complete placental abruption and the death of the child. Accordingly, treatment in this case will be serious, in a hospital setting. Even in the absence of bleeding, a pregnant woman with such a diagnosis needs rest, including sexual rest!
Physical education, swimming pool, long walks, traveling, work are contraindicated.
Let's talk right away about premature abruption of a normally located placenta. As the name suggests, the placenta in this case is in its intended place, but leaves it earlier than expected. Normally, the placenta separates only after the baby is born - in the third stage of labor. If this happens earlier, emergency surgery is necessary to save the life of mother and child! In cases where detachment occurs in a small area, they try to stop it and maintain the pregnancy; but even with a minor episode of bleeding, the danger of renewed detachment remains until childbirth.
The causes of premature placental abruption can be injuries, blows to the abdominal area, various chronic diseases of the pregnant woman, leading to defects in the formation and blood supply of the placenta (diseases of the heart, lungs, kidneys, etc.). Various complications of pregnancy can also lead to premature placental abruption, most often it is gestosis - a complication in which all organs of the pregnant woman and the fetus suffer (it is manifested by increased blood pressure, the appearance of protein in the urine, and edema). In any case, premature placental abruption is a very serious complication, and it is treated only in a hospital setting!
Attachment of the placenta
During pregnancy, the placenta may be in its place, but not properly attached to the wall of the uterus. It is usually associated with the lining of the uterus and is easily separated after the baby is born. But as a result of inflammatory changes in the wall of the uterus or the placenta itself, it can tightly attach to the mucous membrane, grow to it and even grow into the muscle layer. In the latter case, everything is very serious: the woman may lose the ability to give birth to children. If the attachment is tight, the doctor, under anesthesia, inserts a hand into the uterine cavity and separates the “adherent” placenta.
Finishing the conversation about the placenta, I would like to emphasize that no misfortunes happen to us just like that. Pathology of the placenta, as old doctors said, does not occur “in the midst of complete health.” Dear future mothers! Take your health seriously both before and during pregnancy!
Multiple pregnancy occurs in 0.7-1.5% of pregnant women. The reason for the increased attention of obstetricians and gynecologists to this problem is the high risk of complications during pregnancy and childbirth. I will tell you how to carry and give birth to healthy twins using the example of my own practice.
Case study
Svetlana, 32 years old, came for consultation. Here is her letter: “Hello, Olga! Help me please! I'm currently 22 weeks pregnant. I have twins. I couldn’t get pregnant for a long time, I was treated, and now I’m pregnant. Pregnancy isn't easy. The first 4 months there was toxicosis, heartburn, insomnia, and my back hurt badly. I ate almost nothing. Now I feel better, but periodically I have pain in the lower abdomen. The doctor intimidates: he says that I can’t stand both of them. Tell me, Olga, is it necessary to go to the hospital for examination and treatment, and how to endure a double? Thank you!". So, let's figure out what dangers a multiple pregnancy entails, and how to endure it?
What is chorionicity?
The outcome of multiple pregnancy is influenced by chorionicity - the correspondence of the number of placentas to the number of fetuses. The so-called monochorionic (MC) type of placentation, in which there is one placenta for two (identical twins), is unfavorable.
The formation of MC placentation is noted if, on days 4-8 after fertilization, one blastocyst (embryo) divides into two. Identical twins in this case will have a common placenta, but two separate amniotic sacs.
If the division of the embryo occurred immediately after conception (on days 0-4) or after IVF, bichorionic (BC) twins may occur. At the same time, twins are also considered identical, because they came from the same egg. The babies will live in different “houses” (amniotic sacs) and, most importantly, have separate placentas. The presence of two placentas in twins compared to one is more favorable for the course and outcome of pregnancy, since it is 3-4 times less likely to lead to the death of the fetus.
One placenta for two: why is it dangerous?
As we have already said, with MC twins there is one placenta for both. In this case, the vessels supplying blood to the embryos are connected to each other (anastomosed). Blood redistribution may occur unevenly. As a result, one fetus gives blood (donor), the other accepts (recipient). This is how feto-fetal blood transfusion syndrome (FFBTS) develops.
With FFH, the recipient fetus experiences polyhydramnios, hydrops, and heart failure; the donor has oligohydramnios and hypoxia (lack of oxygen). In addition to the development of FFFR, in the presence of one placenta for two, growth retardation syndrome (GRS) of the fetus/fetuses is quite often observed. FFH and SZR are the main causes of late intrauterine death of the fetus/fetuses in the 2nd and 3rd trimesters.
Svetlana did an ultrasound. According to the results of the study, she was diagnosed with monochorionic twins. The weight of the fetus at week 23 was: 371 g for the recipient (normal) and 242 g for the donor (below normal). The recipient was found to have polyhydramnios, the donor - oligohydramnios. According to Doppler measurements, the donor fetus showed signs of anemia (lack of hemoglobin) and hypoxia (oxygen starvation).
Svetlana was very worried about the established diagnosis of FFS and further tactics. The girl asked for clarification on how to treat such abnormalities, and is it possible to save the babies?
Laser coagulation of blood vessels between two fetuses
Currently, the main method of treating CM placentation is fetoscopic laser coagulation of vessels (anastomoses) between fetuses, due to which both babies suffer. The intervention is carried out after ultrasound determination of the location of the placenta, the anastomoses located in it, the septum between the fetuses and the place of attachment of the umbilical cords.
A special instrument (fetoscope) is inserted into the recipient's amnion cavity under ultrasound guidance. Coagulation of blood vessels between fetuses is performed with a laser. The surgical intervention ends with drainage of amniotic fluid until its quantity normalizes. After laser treatment of SFG, half of the patients give birth to both or one healthy child.
I explained to Svetlana that laser coagulation of blood vessels was indicated for her, but the choice was only hers. Of course, it was very difficult for the young woman to make a decision, because we were talking about the lives of unborn babies. She got acquainted with detailed information about SFG, treatment methods, and possible complications. And she agreed to laser surgery.
Svetlana was hospitalized in the hospital. The intervention lasted several hours. The operation was performed by two surgeons in the presence of a neonatologist under general anesthesia. The girl was discharged home on the third day after the operation. She had no bleeding or pain in the lower abdomen.
The young woman was happy! In order to maintain pregnancy, she was prescribed natural micronized progesterone (utrogestan) in vaginal form. Now she was determined to carry twins and was interested in proper nutrition.
Proper nutrition during multiple pregnancy
Every pregnant woman with multiple pregnancy needs to eat well and rationally, consuming at least 3500 kcal per day. The total weight gain during the entire pregnancy should be about 18–20 kg. In this case, weight gain in the first half of pregnancy (at least 10 kg) is especially important to ensure the physiological growth of the fetus. Otherwise, complications are inevitable - malnutrition and delayed development of the fetus.
Also, when composing your diet, you must remember that during pregnancy, especially multiple pregnancies, a woman’s need for iron increases sharply. Therefore, a pregnant woman’s diet must contain foods that include iron and animal proteins: meat, liver, fish, dairy and fermented milk products, buckwheat porridge, raw vegetables (carrots, apples, cabbage) and fruits.
However, it is not always possible to compensate for iron deficiency in a pregnant woman only with the help of a special diet. After all, no more than 6% of iron is absorbed from food. Therefore, in addition to good nutrition, expectant mothers carrying twins or triplets should use iron supplements to prevent anemia. They are highly effective, safe, easy to use, well tolerated and, most importantly, provide the body with up to 30-40% of the iron contained in the preparation.
My patient ate well throughout her pregnancy. By week 29, the weight gain was 18 kg! I note that for a multiple pregnancy this is a normal increase. However, the hemoglobin level was low (90 g/l), despite the consumption of iron-containing foods. Due to the detected anemia, I recommended that Svetlana use the drug Ferlatum Fol. While taking it, my hemoglobin level quickly recovered! In the meantime, it was time to think about childbirth...
Childbirth with twins
It is advisable to carry out delivery of women with multiple pregnancies in a high-level maternity hospital (perinatal center), capable of providing qualified care with neonatal resuscitation. It should be taken into account that a pregnancy with twins is considered post-term from 39 weeks of gestation. Therefore, the optimal timing of delivery for multiple births is 37 and 38 weeks of pregnancy. The timing of childbirth with monochorionic type of placentation depends on the condition of the fetus. With SFFG, pregnancy is prolonged until 37-38 weeks. If necessary and there is a risk of death of the fetus/fetuses, a cesarean section is performed earlier, starting at 32-33 weeks. Svetlana had a caesarean section at 34 weeks. The children were born premature, weighing 1,733 g and 1,364 g. But the young mother was happy! She said: “Since God gave us babies, that means he helped us keep them!” Happy pregnancy and successful birth! Always with you,
In some African tribes, multiple births were considered a curse, and in some cases the second child was even killed. Among the American Indians, on the contrary, it was believed that twins born alive had divine superpower. At the same time, the very fact of such a birth was surrounded by special rituals, and children and their parents were given badges of honor. Europe also contributed to the cultivation of superstitions around multiple pregnancies: in the Middle Ages, there was a view of multiple pregnancies as evidence of adultery, since the second child was supposed to have a second father.
Causes and types of multiple pregnancies
Let's look at them using the example of twins, as the most common type of multiple pregnancy. It has now been established that the causes of multiple pregnancies can be two different processes.
The first (and most understandable) is the fertilization of two eggs by two different sperm. In this case, two independent embryos (or zygotes) are formed. This pregnancy is called bizygotic. Among multiple pregnancies, 2/3 are like this, that is, the majority.
The mechanisms for the formation of bizygotic twins, in turn, can also be of two types. The first is the so-called multiple ovulation, when two eggs mature in one cycle, which are then fertilized by two sperm. The cause of multiple ovulation may be the formation of hormones. It is this mechanism that is used to obtain several eggs during in vitro fertilization: during “in vitro conception”, to increase the likelihood of success, with the help of medications, several follicles - vesicles with eggs - mature in the ovary during one cycle.
However, another mechanism is also possible when, for reasons that are not entirely clear, after fertilization of the first egg, the maturation of the next follicle is not inhibited and ovulation and fertilization occur in the subsequent cycle. Thus, with an interval of approximately 28 days, two fertilized eggs sequentially enter the uterus. Such children are born together, but the length of stay in the womb (and therefore the weight and degree of maturity) of the second child will be 4 weeks less. Indirect evidence of the possibility of such a mechanism in humans are some results of ultrasound studies, when a doctor who discovered a singleton pregnancy in the early stages notes the appearance of a second fertilized egg in the uterine cavity after 4-5 weeks. It should be noted that there is no rigorous evidence for the existence of this mechanism yet. It is clear that bizygotic twins can be either same-sex or opposite-sex.
The remaining one third of the total number of twins develops from one egg and is called monozygotic. These twins still pose a mystery to obstetricians and often cause the most problems during pregnancy. The mystery lies in the fact that at a certain period of development, the zygote, for unknown reasons, is divided into two viable halves. Moreover, from a formal point of view, one of the future embryos is a clone of the other.
The division of an egg to form monozygotic twins can occur between 2 and 15 days after fertilization of the egg. If the division of the egg occurred on the 2-3rd day, then each of the halves of the zygote has full potential for independent intrauterine development. That is, two embryos are formed, each of which has a separate chorion (precursor of the placenta) and its own separate amniotic cavity (fetal bladder). Such twins will be called monozygotic (from one zygote), bichorionic (with two placentas) and biamniotic (with two membranes). If the division of the zygote occurred from the 4th to the 7th day after fertilization, then the mass of cells from which the chorion and then the placenta will subsequently develop has already separated from the main group of cells forming the body of the embryo. Thus, the separation process will only affect this last group. The result is twins with one common placenta and two amniotic cavities. This type of twins is called monochorionic biamniotic (one placenta, two membranes).
If the separation occurred in the interval of 8-12 days, then only the separation of the embryos occurs. In this case, they share not only the placenta, but also the amniotic cavity. Such twins are called monochorionic monoamniotic (one placenta, one amniotic sac).
Separation at 13-15 days after fertilization can no longer be completed completely and leads to developmental defects. In this case, twins can be joined by any part of their bodies. An example of such an incomplete separation is the famous Siamese twins. In a sense, even early separation, when the separation of the embryonic bodies is complete, cannot be considered a completely normal process, since the incidence of malformations in one or both monochorionic twins is several times higher than in the case of a singleton pregnancy or bizygotic twins.
It is quite obvious that since monozygotic twins came from the same egg, their gender, blood type and chromosome set should be the same. However, it happens that in monozygotic twins, one of the fetuses is born with a developmental defect, while the other does not have it. Obviously, the cause of this cannot be a genetic (chromosomal) pathology. In this case, the only reason can only be a defect in the bookmark - i.e. the influence of factors external to the embryo on the development of the internal organs of the embryo in the first trimester. These factors may include physical (ionizing radiation), chemical or infectious (viruses, bacteria).
Diagnosis and observation
Modern ultrasound technology makes it possible to detect multiple pregnancies at the earliest stages of development. Usually, already at the 5-6th week, two fertilized eggs are clearly visible, a little later the bodies of the embryos become visible and the contractions of their hearts are clearly recorded. At a later stage of pregnancy, it becomes possible to determine the number of placentas, the presence of partitions between the membranes and the dynamics of fetal growth. These data are very important for determining the synchrony of fruit growth. Since monozygotic twins have an increased likelihood of developing malformations, special attention is paid to the search for this pathology.
In twins, the incidence of spontaneous termination of pregnancy (spontaneous abortion) is increased. Probably, such spontaneous abortions of one of the bizygotic fetuses can explain the facts when, in the early stages of pregnancy, a woman experiences short-term bleeding, after which the pregnancy continues and ends relatively normally as a singleton.
Features of pregnancy
Numerous ultrasound studies of twins show that in the case of their normal development, the growth dynamics of each fetus up to 30-32 weeks of pregnancy corresponds to the growth of the fetus in a normal singleton pregnancy. Of course, a lot depends on the place where the placenta is located in each fetus. The most favorable place for the placenta to attach is the fundus, anterior and posterior walls of the uterus. The lower the placenta is, the fewer so-called spiral arteries of the uterus that supply blood to the placental villi, and the worse its nutrition. This is not a random dependence, but a completely justified biological mechanism that makes low placentation disadvantageous in order to reduce the likelihood of central placenta previa (the so-called condition when the placenta completely covers the internal os of the cervical canal uterus and makes the natural birth of a child impossible). If placentation occurs low enough, then the process of placental growth goes in the direction of better nutrition, and it seems to shift upward. This is what explains the “raising” of the placenta at a low position in the case of a singleton pregnancy.
It is clear that if the placenta of one of the fetuses is low enough, then the likelihood of developing placental insufficiency increases, one of the manifestations of which may be gestosis.
After 32 weeks of pregnancy, the rate of increase in length and weight of twins decreases. By 37-38 weeks, the weight of each of these fetuses is less than the normative weight of a fetus from a singleton pregnancy. Studies show that the weekly weight gain of each twin fetus after 32 weeks corresponds to the weekly weight gain of the singleton fetus at the same time. Thus, it can be assumed that at the end of the third trimester, the main limiter on the growth of twin fetuses is the ability of the mother’s body to deliver oxygen and nutrients to the uterus. Obviously, in this situation, the body of a mother carrying a multiple pregnancy experiences significant additional stress. By the end of pregnancy, the overall increase in the mother's body weight in the case of twins is 30% greater than in a singleton pregnancy. The volume of circulating blood additionally increases (by 10-15%), but there is no corresponding increase in the number of red blood cells. Therefore, pregnant women with twins are more likely to experience anemia - a decrease in the number of red blood cells. To prevent the development of this condition, women with multiple pregnancies should eat more protein and be sure to take iron supplements.
During the development of a multiple pregnancy, the internal volume of the uterus increases at a faster rate than in the case of a single pregnancy. The uterus reaches the volume characteristic of full-term pregnancy earlier. At this point, the uterus’s own regulatory mechanisms increase its contractile activity, preparing for the upcoming birth. Therefore, with multiple pregnancies, labor often begins prematurely. But this is no reason to worry.
Interestingly, the incidence of multiple pregnancies is not the same in different countries and on different continents. It is possible that this is in some way connected with the ethnicity of the population of these countries. Thus, in Japan there is the lowest incidence of twins - 0.6% (i.e. 6 per 1000 births), in Europe and the USA it ranges from 1.0% to 1.5%, and in Africa this figure is the highest. So, in Nigeria this figure reaches 4.5% (45 per 1000). Such differences apply exclusively to bizygotic twins. Monozygotic twins occur with remarkable consistency in all parts of the world. Their frequency is 0.4% (4 per 1000). It was found that the likelihood of bizygotic twins is inherited - mainly through the maternal line. This may be due to the inherited increased synthesis of folliculin, a hormone that affects the number of eggs maturing in the ovary.
Complications of pregnancy with monochorionic twins
The term "monochorionic twins" suggests that the placenta has not separated between the two fetuses and they receive oxygenated blood from the same placenta. In this situation, it can be assumed that some of the vessels belonging to the vascular placental system of one fetus are connected to the same vessels of another fetus. Such connections of vessels are called anastomoses. Indeed, upon careful examination of the placentas, it turned out that in 98% of cases in monochorionic twins, the placentas are connected by vessels. However, in only 28% of cases, blood is pumped through these connections from one fetus to another. The reasons for this flow of blood are still not entirely clear. In this situation, the fetus from which blood is pumped acts as a donor, and the other as a recipient.
When such a complication occurs, called feto-fetal transfusion syndrome (FTTS), the discharge of blood from one fetus to another leads to bleeding of the donor and, conversely, to an overload of the recipient’s circulatory system. If feto-fetal transfusion is not stopped, it can quickly lead to the death of the donor, and then the recipient. Unfortunately, there are no effective methods for preventing and treating transfusion syndrome. The only way to prevent the development of feto-fetal transfusion syndrome today is therapy aimed at improving placental circulation.
Summarizing the currently known information about multiple pregnancies, we can draw the following conclusions:
- Multiple pregnancy places special, increased demands on the mother's body. Of course, doctors do not consider it as a pathology, but they believe that such a pregnancy (especially with monochorionic twins) requires closer attention from medical personnel.
- The likelihood of developing placental insufficiency and gestosis during a multiple pregnancy is greater than during a singleton pregnancy. Consequently, all measures aimed at preventing the development of these conditions are carried out from the beginning of the second trimester. Particular attention is paid to the full protein nutrition of the expectant mother: taking iron supplements and vitamins.
- It is advisable to give birth to a woman with twins in a high-level maternity hospital (perinatal center) with powerful, qualified neonatal resuscitation. It is clear that the frequency of surgical delivery (caesarean sections) in multiple pregnancies is significantly higher than in singleton pregnancies. However, the method of delivery depends on many factors: on how the pregnancy occurred - spontaneously or with the help of IVF, on the nature of the twins (bichorionic or monochorionic), on the nature of the location of the fetuses, on the health status of the expectant mother and other factors. In each case, labor management tactics are developed individually.
Double placenta (placenta duplex)
1. Small medical encyclopedia. - M.: Medical encyclopedia. 1991-96 2. First aid. - M.: Great Russian Encyclopedia. 1994 3. Encyclopedic Dictionary of Medical Terms. - M.: Soviet Encyclopedia. - 1982-1984.
See what “double placenta” is in other dictionaries:
- (placenta duplex) see Placenta bilobed... Large medical dictionary
Large medical dictionary
- (placenta bilobata, placenta bipartiata; synonym: double placenta, double-disc placenta, bilobed placenta) a variant of the structure of the placenta in which it consists of two separate parts of approximately the same size, connected by non-permanent... ... Medical encyclopedia
- (Primates), an order of mammals that includes humans, apes and other apes, as well as prosimians. Perhaps the tupai from Southeast Asia should also be included in this group. The name primates, meaning first, leading, was given to the order... ... Collier's Encyclopedia
- (Mammalia) the highest class of vertebrates. Their main features are the following: the body is covered with hair; both pairs of limbs serve mostly as legs; the skull is articulated with the spine by two occipital tubercles; the lower jaw articulates... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron
- (uterus, metria) a special section of the genital ducts in female animals and women; is an expanded part of the Oviduct. M. has a powerful muscle wall and is well supplied with blood. Uterus in animals. M. is present in roundworms... Great Soviet Encyclopedia
Or lemurs in the broad sense (Prosimiae) are a detachment of mammals characterized by the following characteristics: the entire body is covered with thick and long hair, with the exception of the end of the nose; the large orbital sockets are surrounded by a complete bone ring, communicating... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron
Or lemurs in the broad sense (Prosimiae) are a order of mammals characterized by the following characteristics: the entire body is covered with thick and long hair, with the exception of the end of the nose; the large orbital sockets are surrounded by a complete bone ring, communicating... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron
Professor William Crooks and the materialized phantom "Katie King". Medium Florence Cook is lying on the floor. Photograph from 1874 Materialization in occultism, parapsychology and spiritualism is a phenomenon characterized by the emergence ... Wikipedia
Or lemurs in the broad sense (Prosimiae), an order of mammals characterized by the following characteristics: the entire body is covered with thick and long hair, with the exception of the end of the nose; the large orbital sockets are surrounded by a complete bone ring, communicating only... ... Encyclopedia of Brockhaus and Efron
