Multiple pregnancy

Multiple pregnancy is a pregnancy in the presence of more than one fetus in the uterine cavity. Despite the increased incidence of multiple pregnancy in recent years, it still correlates with an infrequent( 0.7-1.5%) phenomenon, and more often( on average 1 birth in 80), two babies appear in the finals in the finals. Multiple pregnancies with three, four and even five fruits are rarely recorded.

It has been reliably proven that there is a predisposed predisposition to the birth of twins, and not only on direct lines( from mother or grandmother) to inheritance lines, but also on lateral ones( for example, from aunts).In such families, a second multiple pregnancy is often recorded.

In addition to heredity, the likelihood of multiple pregnancies increases the use of hormonal drugs for the purpose of contraception or the stimulation of ovulation for IVF.

To understand the mechanism of the formation of two or more fetuses in the uterus, it is necessary to recall the mechanism of development of ordinary, singleton, pregnancy.

Ovaries are responsible for reproductive function in women. Each month, they undergo successive hormonal and structural changes that ensure the maturation of the egg and the potential for conception. Egg cells develop in special formations - follicles. They are laid in the ovaries initially and, when the girl overcomes the period of puberty( pubertal), begin to actively "grow up" and become a source of eggs.

The follicle and the egg in it are maturing symmetrically. If you divide the menstrual cycle in two, the first half( phase) will correspond to the period of formation of the follicle, when it begins to actively increase, accumulate fluid and stimulate the growth of the egg by secretion of the hormone estrogen. When the egg completely ripens, that is, it becomes capable of fertilization, the follicle breaks down and releases it. This moment is called ovulation.

Ovulation is a kind of boundary between the end of the first and the beginning second phases( halves) of the cycle. In the second phase of the remnants of the follicle formed a yellow body - a small hormonal structure, secreting the hormone progesterone. The yellow body in the absence of pregnancy functions briefly, collapsing shortly before the onset of menstruation. And if successful conception has taken place, it continues to synthesize progesterone to maintain pregnancy until this function is taken on by the placenta.

Both phases of the menstrual cycle are accompanied by hormonal production of the pituitary: in the first phase, it secretes the stimulating growth of the follicle FSH hormone, and in the second - LH, the luteinizing hormone responsible for the correct functioning of the yellow body. By analogy with the names of hormones of the pituitary gland the first phase of the cycle is called follicular, and the second - luteal.

And what happens to the egg when it leaves the ovary? To fertilize, it needs to unite with the male sex cell. After leaving the ovary, the egg moves to the fallopian tube. Spermatozoa, breaking the cervical and then the uterine cavity, also come from the vagina into the fallopian tube, where fertilization takes place. After the coalescence of the two sex cells, a zygote is formed, due to the wave-like movements of the walls of the uterine tube, it advances toward the uterine cavity, enters it and is implanted( implanted) into the endometrium.

In the absence of fertilization for two days, the oocyte dies.

As a rule, during one menstrual cycle only one egg has time to "grow up", and the pregnancy ends with the birth of one fetus. Multiple pregnancy develops:

- under condition of simultaneous fertilization of two or more oocytes, that is, when several full-length zygotes are formed. In this situation, children are called raznoyaytsevymi( dizygotic) or twins, they have a different set of genes, can be different sexes and not similar to each other;

- if a single ovum is fertilized, which is then divided( more often in two), and the fetus develops from each divided part, these children are called twins. Monozygotic( identical) twins have an identical set of genes, that is, they are always of the same sex and are very similar in appearance.

More often, fetal twins are born, and in 99% the multiple pregnancy terminates with the birth of two children.

Increased cases of multiple pregnancies are directly related to the widespread use of IVF techniques, when several embryos are "inserted" into the uterus to increase the chances of success( "at least one survives"), and in the end, two or even three survive.

The course and management of multiple pregnancies differs from the usual, as the body experiences an increased load. As a rule, the multiple pregnancy is completed earlier, and the birth requires careful observation.

Multiple pregnancy results in successful delivery only with a small number of embryos in the uterus. The most prolific pregnancy with a favorable outcome was limited to ten fruits, and the most prolific pregnancy with a miscarriage in the finals is twelve.

Causes of multiple pregnancy

Multiple pregnancy, in spite of the low occurrence, is not a deviation from the norm, and all the born children do not differ from those in the case of singleton pregnancy.

As a rule, in most cases, ovulation occurs in only one ovary, and a single egg can fully mature in one cycle. Two or more fetuses( embryos) develop in cases:

- When in both ovaries at a time, one ovulatory cycle, there are two mature follicles, and after ovulation in both fallopian tubes there are two eggs that can symmetrically fertilize, and then"Go down" into the uterine cavity for further development.

By the same mechanism, multi-egg( two-, three-, and so on) embryos are formed, if two( less often more) ripened follicles per one cycle are located in one ovary. Then their symmetrical fertilization occurs in one tube.

- If a single follicle with a single ovum ripens in the ovary, but then the egg is divided, and each of its detached part begins to develop independently. Embryos under such a mechanism of development are obtained by monozygotes.

Further development of fetuses in the uterine cavity also depends on the number of eggs from which they are formed. If several ovules from different follicles were the source of pregnancy, each developing embryo has an autonomous "place of development" - its own placenta and fetal( chorionic and amniotic) membranes. By this mechanism, more than 70% of double-sided twins develop.

In embryos belonging to a single egg, development depends on the moment when this egg was fragmented. If it is divided on the first day after fertilization, then each embryo will have its own placenta and membranes, as in the case of multizygotic pregnancy.

When the fission period started on the 3rd - 8th day, around each embryo formed its own amniotic membrane( "fetal bladder"), but they have one placenta.

A later( up to 13 days) crushing of the egg leads to the development of embryos in a single fetal bladder with a single placenta.

Very rarely the division of the egg starts after the 13th day after fertilization, as a result, fused embryos develop.

The opinion among women that a multiple pregnancy is the result of consecutive( simultaneous) fertilization of an ovum with several spermatozoa is absolutely wrong. After conception, the progesterone effect of the yellow body excludes the full development of other follicles, so the fertilization of one egg is possible with only one sperm.

In addition to genetic predisposition, which significantly increases the likelihood of multiple pregnancies, there are several other factors provoking its development:

- Age. As a rule, multiple pregnancies are more often diagnosed in women over 30 years old. Apparently, a natural age reduction in the number of ovulatory cycles after thirty years results in a peculiar deposition of hormones, which in the case of fertilization play the role of hyperstimulants.

- With prolonged use of hormonal contraceptives. Their contraceptive effect is based on the mechanism of suppression of ovulation, so when a woman stops taking them, there is a symptom of withdrawal: according to the feedback mechanism, hormone stimulating hormones are synthesized more.

- Due to artificial conception, that is, extracorporeal( "in vitro") fertilization, or IVF.Wishing to become pregnant with a woman to achieve the greatest probability in the uterine cavity is introduced several embryos. More often in the uterus there is only one of them, but sometimes two survive and develop, more rarely - more.

- If there is an incorrectly formed uterus( developmental defect), namely, its doubling. Double can only be the body of the uterus in the presence of one cervical cavity, then it acquires a bicornic form. Also there are doubled uterus, cervix and vagina. If each of the doubled genital structures is developed and functions fully, neither complete nor absolute duplication of the uterus does not prevent the development of pregnancy. In the case of twins, embryos are hatched symmetrically in each of the uterine cavities.

Symptoms of multiple pregnancy in the early stages of

Multiple pregnancy at the onset of development does not have any distinctive clinical manifestations, therefore requires additional diagnostic laboratory and instrumental studies. Women who have multiple instances of multiple pregnancies in the family usually do not rule out the existence of such a pregnancy. Also, the possible simultaneous presence of two developing embryos in the uterus is prevented by successfully surviving artificial insemination or hormonal stimulation of ovulation.

Clinically, early signs of multiple pregnancies are similar to those in singleton pregnancy. The very first of these is the absence of another menstruation. At this stage, most women themselves resort to rapid diagnostic techniques, and only when they receive a positive test result are they referred to a specialist.

Express diagnostics is carried out at home and allows to ascertain with high( 97%) authenticity pregnancy with minimal( more than 1 day) menstrual delay. It should be explained that the number of days of menstrual delay does not correlate with the "age" of the embryo. Conception, that is, the fusion of the two sex cells in the zygote, occurs in the cavity of the fallopian tube, after which the fetus must be inserted and implanted( implanted) into the endometrium, where the pregnancy will begin. Usually it takes about 2 weeks for a zygote. After implantation, the secretion of the "pregnancy hormone"( hCG) - the chorionic gonadotropin - begins. It is necessary for the correct formation of the fetus, its preservation in the uterus, as well as for the suppression of ovulation in order to prevent the next conception. Express methods allow to determine the presence of hCG in urine, that is, to establish only the fact of pregnancy, and to determine its term, as well as the number of embryos, they can not. Moreover, a positive test will be with ectopic embryo localization.

The gestation period is correlated with the concentration of hCG.Since the moment of ovulation, and therefore of conception, is calculated with small errors, to determine the exact period of pregnancy, it is necessary to measure the level of chorionic gonadotropin in the blood and compare it with the delay period.

The concentration of hCG in multiple pregnancy is higher. It is conventionally believed that once a hormone synthesizes the placenta, doubling it doubles, and if doubled( in comparison with the norm) the indicators continue to grow along with the period of pregnancy, the probability of the birth of two fruits is very high. To the situation with triplets( and more fruits), this logic does not apply.

The higher content of hCG in multiple pregnancy is a relative diagnostic feature, since each multiple pregnancy is not similar to the others. In addition, quantitative hCG increases with IVF even in single-pregnancy.

It is possible to suspect the presence of multiple pregnancies in the early stages even in the process of palpation of the pregnant uterus, when its size does not correspond to the declared time of delay. It is in this situation that additional laboratory determination of the concentration of hCG in the blood is required. Thus, the earliest signs of multiple pregnancies - menstrual delay, uterine enlargement with palpation and a positive express test - confirm the presence of pregnancy itself, but do not specify the number of developing embryos.

The most reliable method is ultrasound scanning, which already in the early stages( from 5 weeks) "sees" a multiple pregnancy. Further management of multiple pregnancies depends on the number of embryos and placenta visualized in the uterine cavity, as well as on their rates of development, so ultrasound control is performed more often.

The course of multiple pregnancies

Since the bearing of several fruits at the same time, after all, is not a normal situation, it is logical to assume that the uterus, as well as the whole organism of the pregnant woman as a whole, is more adapted to single-pregnancy. Therefore, the bearing of two or more fruits is always accompanied by a greater load and requires the realization of all the physiological reserves of the mother's body.

The course of multiple pregnancy has several significant features that distinguish it from pregnancy in one fetus, such as:

- Significant increase in the volume of circulating blood( BCC).As a rule, the presence of yet another "living organism" in the body of a pregnant woman requires more nutrients and vitamins, which are delivered to tissues with blood. The volume of circulating blood in single-pregnancy increases by 40%, and in the case of a multiple pregnancy - by 50% - 60%, which in turn provokes the appearance of edema and increases blood pressure.

- Anemia. In fact, it can be correlated with the physiological state, provoked by increased BCC.Since the volume of circulating blood is replenished by plasma, iron stores and hemoglobin levels, respectively, are not replenished, which means they are reduced.

Anemia due to iron deficiency is diagnosed in every second pregnant twin, and if there are more than two fruits in the uterus, its frequency increases 100%.

- gestosis( toxicosis).It is diagnosed in 45% of pregnant women. It is formed much earlier than in single-pregnancy, it is more pronounced. This is due to an increase in the placental mass( hyperplacenta).

- Exacerbation of existing extragenital pathology. Occurs in all women bearing more than one fetus against the background of a significant load on the cardiovascular, respiratory, excretory and other systems. In this case, the pregnant woman is monitored together with related specialists.

- Increased load on adjacent organs. Increased significantly the uterus presses and displaces adjacent organs( liver, kidneys, diaphragm, bladder, intestine), which can not work in the previous regime.

- Reduction of duration of pregnancy. There is a direct relationship between the number of developing embryos and the time of onset of labor. In normal, singleton, pregnancy signal for the onset of labor is an increase in the size of the uterus to certain, perceived by the body as the final values. When several fruits are born, the uterus reaches these dimensions much earlier, therefore, the delivery is induced earlier.

At double pregnancy is more often completed on the 37th week( 260 days), with triple - on the 35th( 247 days).

- Unequal development of all fruits. The more embryos present in the uterus, the more difficult it is for the body to maintain their symmetrical development. Therefore, one( with double) or more( with triple or more) fruits can develop with a lag. This does not mean that a multiple pregnancy always ends with the birth of only one fully developed child, because the differences in the rates of development can be expressed in different ways. As a rule, most of the births after the completion of dvaens are successful, but even with a favorable pregnancy, the risk of delaying the development of one of the fetuses remains tenfold.

Due to the above reasons, multiple pregnancies significantly worsen a woman's well-being: she often feels pelvic pain, fatigue, dyspnea, heartburn, defecation( constipation) and urination, which becomes frequent.

It should be noted that a multiple pregnancy, although it is less common, is not a pathology. Therefore, all the uncomfortable symptoms accompanying it are provoked not by pathology, but by a greater burden on the body. With the proper management of pregnancy by professionals and strict observance of all recommendations from the future mother, multiple pregnancies proceed peacefully and end with the successful birth of healthy children.

Features of Multiple Pregnancy

Each multiple pregnancy is unique in its own way, therefore it always requires an individual plan of supervision and subsequent delivery.

Features of the formation of multiple pregnancy is more convenient to consider the example of twins. As already mentioned, two embryos can develop from a single fetal egg or from two. However, this developmental features of the two do not end there.

With dizygotic double, each fertilized egg becomes a source of placenta formation, and each of the growing fruits is eventually isolated from the other's own fetal( amniotic) and chorionic membranes. Thus, the septum between the two fruits consists of four layers. According to such anatomical features, dvuzygotic twins are called Biamniotic Bihorial. The frequency of such twins( among all others) is close to 70%.

If twins develop from a single zygote, the further development of embryos is ambiguous and directly related to the timing of the onset of the division of a fertilized egg.

The unicellular stage of embryo development( zygote) lasts no longer than 30 hours. Then the zygote begins to break up, that is, to divide into cells, and their number in the end is always a multiple - two, four, eight, and so on. The higher the number of cells, the larger the size of the embryo. Such crushing does not always begin at the same time.

When the division of a single egg starts in the first three days after conception, the further development of a two-fetal pregnancy is analogous to that of a double-jawed twin: two amnions, two placentas are formed, and the fruits are separated by a four-layer septum. Therefore, the twins formed in this way are also called bihorial biamniotic.

Sometimes the egg can begin to split in the interval 3 - 8 days. In twins, at this time, the common placenta is formed, but different amniotic membranes, and at the septum between them there are only two layers - a monochorion bi-amniotic twins.

Development of double monochorionic mono-amniotic type is quite rare. In the fragmentation of the zygote in the late( 8th - 13th day) period, two embryos have not only the common placenta, but also one for two amniotic sacs, and the septum between them is absent.

It is considered unfavorable to start the crushing of the egg in a later period, that is, after 13 days. In this situation, both embryos fuse together.

Ultrasound scanning makes it possible to study the anatomical features of multiple pregnancies already in the first trimester. Its course and outcome is determined not by zygote, but by the amount of placenta( choriality).The most unfavorable structural option is a monochorionic multiple pregnancy, that is, identical twins.

In later terms, the presence of two or more fetuses is diagnosed in a routine obstetric examination, that is, with external palpation, which determines the presence of several heads and small parts( limbs).In this case, the location of each child is also more often determined.

Reliability of multiple pregnancy helps to establish and auscultatory method, allowing you to listen in different parts of the uterus heart tones of the fruit. At earlier times, special equipment is required for this, and the doctor will listen to the late beating of several hearts with a conventional stethoscope.

The total weight gain of pregnant women with multiple births should be higher than in single pregnancy. Optimum is considered an increase in 20 or 22 kg. This increase in weight is certainly accompanied by increased stress on the body, because the heart, blood vessels, kidneys and other organs and systems work at the limit of their capabilities.

Multiple pregnancy requires enhanced nutrition. In multiple pregnancies, each of the developing fetuses needs the right amount of calories, oxygen, nutrients and vitamins. The future mother also needs them. To compensate for these needs, you need a properly adjusted diet.

Another feature of the multiplane is iron deficiency anemia, triggered by depletion of iron stores. If in single-pregnancy pregnancy anemia is classified as a negative symptom, when it is multiplied it is considered physiological, but always compensate for medication.

For quite understandable reasons, the observation of multiple pregnancies differs from that in the presence of a single fetus in the uterus. Patients need more careful observation, so they should visit the doctor more often. The frequency of monthly visits to the women's consultation, as a rule, is determined individually. In addition to a gynecologist, a therapist observes a multiple pregnancy, and in the presence of extragenital chronic pathology, other specialists join the observation.

Pregnant with multiple pregnancy requires a restriction of physical activity, as well as an increase in the amount of time for sleep, including during the day.

Unfortunately, many pregnant women( including one fetus) incorrectly correlate their state of health with the course of pregnancy and therefore do not always adequately respond to the recommendations of specialists. Meanwhile, sometimes about the unsuccessful fetus with a satisfactory state of the mother can be judged only by the results of additional studies. When multiple pregnancy is particularly important to perform all the recommended activities, including agreeing to prevent hospitalization in a day hospital or separation of pregnancy pathology.

Childbirth with multiple pregnancy

With adequate tactics for monitoring multiple pregnancies, it proceeds with minimal negative symptoms. However, even the most successful multi-prenatal pregnancy before its completion requires preliminary hospitalization in the maternity hospital. A number of necessary diagnostic measures are carried out in the hospital to assess the likelihood of complications and determine the method of delivery.

To select the right tactics for conducting the forthcoming births, the specialist needs:

- To know the number of fetuses in the uterus and their estimated weight. Uterine musculature is not always able to "push out" more than two fruits, so it is often chosen operative delivery.

The presence of two large fruits is also sometimes a reason for surgical delivery.

- Evaluate the equivalence of their development. Unfortunately, sometimes embryos develop asymmetrically, and by the time of delivery, not all have the proper level of development. Expressed signs of underdevelopment( hypotrophy) of one or several of the fruits on the eve of birth can mean their non-viability. Sometimes after birth, a fetus with signs of hypotrophy "nurses" in special conditions until the moment when it reaches the necessary level of development.

- Determine to which type of multiple pregnancy this pregnancy relates, that is, set the number of placenta, fetal blisters and so on.

- Set the position of each fruit( head, gluteal).Favorable in terms of natural birth is a symmetrical presentation of the fruit. If the first fruit is in the head, and the next - in the pelvic presentation, the birth safely passes naturally. After the birth of the first baby, the second one is "turned" under ultrasound control so that it also locates correctly.

The transverse position of one of the fruits serves as an absolute reason for operative labor.

- To evaluate the individual psychophysical characteristics of a pregnant woman."Fragile", not distinguished by good physical endurance of a woman, are not always capable of the natural birth of several children at once.

Sometimes multiple pregnancy scares pregnant women, they knowingly assume heavy births, fear them and prefer an operative way. If the doctor does not manage to rid the pregnant woman of such fears and adjust it correctly, the question of the method of delivery is decided individually.

- Get information from a woman's consultation( it is reflected in the dispensary card) about the course of pregnancy and the medications that are being performed. Severe anemia, high blood pressure, signs of impaired kidney function during the bearing of several fruits increase the risk of complications in childbirth.

The process of the birth of several fruits through the natural birth canal is associated with an increased burden on the uterine musculature, so in the birth in the event of a weakening of the labor, the uterus is "helped" medically.

Adequate anesthesia and bleeding prophylaxis are important stages in the management of natural labor in multiple pregnancies.

Operative planning births are used in several cases, namely:

- the presence in the uterine cavity of more than two fruits;

- transverse arrangement of one of the fruits and pelvic - the very first;

- polyhydramnios;

- a complex form of gestosis( stable high blood pressure, high concentration of protein in the urine);

- large fruits;

- the so-called collision of fruits, when they literally cling to each other's heads;

- hypoxia of one or all of the fetuses;

The second multiple pregnancy is also more often resolved surgically.

Many-times, unfortunately, not always happy future mother. At the urging of the woman herself in the early stages, one of the fruits can be removed by reduction( aspiration), thus transforming the pregnancy into a single-fetal one. Reduction is also used after artificial insemination. With IVF, several embryos are implanted in the uterus to increase the chance to "settle down" for at least one. Sometimes, in the end, all or several are viable, so multiparty appears.

Multiple pregnancy complications

Multiple fruit complications can be classified as arising during the development of embryos / fetuses( congenital), and at the time of their birth. And, not all of them are specific, that is, characteristic only for multiple pregnancies.

Specific complications of multiple fetuses are:

- Fruit Growing. Such an anatomical defect is possible in the presence of a common cavity devoid of septum, in which embryos develop. Brushes can be in different departments, beginning from the head, and ending with the sacral zone. Up to 31% of spliced ​​twins are killed already at birth, 34% - in the first day of life. The survival of children with such a defect is determined primarily by the type of fusion and the presence of other anomalies.

- Fetofetal Transfusion Syndrome. If twins have a common placenta( monochorionic), then each of the fruits is communicated with it by individual blood vessels. When development is disturbed between the fruit vessels of twins, joints( anastomoses) appear, and the blood from one fetus starts to be discharged to another. Thus, one of the fruits becomes a donor and experiences a serious nutritional deficiency and, as a result, can develop incorrectly, and more often( 60-100%) is killed in utero. The recipient fetus may also have developmental abnormalities.

- Intrauterine death of one( double) or several fetuses.

- Reverse arterial perfusion syndrome. Also inherent in monochorionic twins, when one of the twins does not have a heart, and often - and the head, and is supplied with blood from a healthy fetus. As a result, both children live at the expense of a single heart, and this provokes heart failure, polyhydramnios, premature death( 41%).

- Unsymmetrical development of fruits. A slight lag in the development of one of the twins is not considered a complication, but if the delay in maturation is significant, the underdeveloped fetus may die in utero.

- Premature( long before birth) death of one fetus. If it occurred early( 1st trimester), then the probability of death and other fetuses increases( 24%).In later terms, the deceased twin becomes a source of intoxication for the living.

These complications, of course, can scare the future mother. However, it should be recalled that they are encountered less and less, as modern diagnostic techniques allow timely detection of any ills and take adequate preventive measures.