How twins appear. Fraternal and identical twins: differences

Twins is the common name for a phenomenon that is commonly called multiple pregnancy among specialists in the field of obstetrics and gynecology.

Twin options

If it turns out that a woman is expecting two children at once, such a pregnancy can be one of two options. The first of them is the formation of so-called identical twins. It occurs if, during the process of conceiving a child, one egg was fertilized, but then, for one reason or another, it was divided into two absolutely identical parts. In this case, future children will also be the same, that is, very similar friend on a friend.

The second option for the development of pregnancy in the case of the simultaneous presence of two fetuses at once is the formation of fraternal twins. This rare case represents a situation when, during the process of conception, two eggs are simultaneously fertilized. In this case, completely independent embryos are formed in the uterine cavity, which are completely different from each other. In fact, as a result of such a pregnancy, children are born as different as if they were born during two different pregnancies.

Twins on ultrasound

As a rule, to find out that the pregnancy is multiple, using ultrasound diagnostics early enough. An ultrasound specialist can determine that you are having twins as early as the fifth week of pregnancy. However, it should be borne in mind that this only applies to fraternal twins, since they are formed from different eggs, which are clearly visible on ultrasound. Outwardly they will look like two dark spots, clearly visualized in the uterine cavity.

As for identical twins, the fact of the egg dividing into two identical parts will be noticeable on an ultrasound a little later. It is possible to reliably establish that you will have identical twins no earlier than 12 weeks of pregnancy. However, in the future, the effectiveness of ultrasound diagnostics for them will be as effective as for fraternal twins.

It should be borne in mind that during the development of two babies at the same time, the uterus in most cases will increase at a faster rate compared to a singleton pregnancy, however, the embryos themselves will most likely have a slightly smaller size and weight compared to the situation when a woman is carrying one child. This will be noticeable on an ultrasound and noted by the doctor, but do not be alarmed by this situation - it is normal for multiple pregnancy.

Let's talk about how to conceive twins or twins. People could not predict the birth of twins, and some of them looked like ordinary brothers and sisters, only they were born on the same day. Before studying the human body, they could not understand the difference; they again attributed it to God’s will.

How to conceive twins now that many couples want to have two children in one fell swoop. And what is the difference between the concepts? Motivation of parents - together children will have more fun growing up and life will be easier. Such children do not know the horrors of loneliness, they are always nearby close person. After all, the connection between twins is very strong. Raising two is certainly more difficult, especially in the first year. But then everything “settles down” and the kids play together and learn everything together.

How twins and twins are born

Why are twins or twins sometimes born? modern science can't explain it either. Why are twins of different sexes all the more so? Such children are generally called “royal twins”, when a family receives a boy and a girl at the same time - a royal order! Beautiful daughter and strong son.

How twins are born and what are the differences:

Monozygotic - at first everything goes as usual. One of many sperm reaches the egg and fertilizes it. Next, the cells divide in two and two organisms develop, indistinguishable from each other, but completely independent in biological terms. Such twins will really be similar and strongly connected throughout their lives. Psychologically, morally and even physically. There are known cases of simultaneous deterioration in the health of both twins when one fell ill. They can be different people in character, but retain many of the same habits. Science cannot tell you exactly how to conceive twins; it does not know the answer to why, at the stage of conception, cells can divide in two and develop in two directions as separate organisms.
Dizygotic - Twins have a similar appearance, but this similarity resembles ordinary family traits. Maybe eyes, height, facial features. However, it is noticeable that different people. Sperm meet two eggs on their way and simultaneously fertilize them. This is how dizygotic twins develop. Often multiple pregnancies are achieved artificially. After IVF, when a woman is given several fertilized eggs at once, with the expectation that one will survive. But most experts are for the natural way.

How to promote twins

Statistics are on the side of lovers of double happiness. Last years women more often hear: “Expect twins.” Maybe this is the reason early start receiving different hormonal drugs— Hormones are found in many birth control pills. That's why some women get fat.

IVF or a course of special treatment, when a woman is prescribed medications that stimulate the ovaries. Increases the chance of producing more eggs at one time. For example, both ovaries “release” an egg. The sperm rush in both directions and voila!

How to conceive twins or twins, there is a probability table. Some doctors believe that the chance of multiple pregnancy is passed on genetically. If there were twins in the family of the father or mother, the likelihood of recurrence is higher.

Calculate the birth of twins according to the calendar

Many women believe in the magic of numbers, but doctors have their own theory. They were able to develop special technique to help in the formation of multiple pregnancies. Most of the recommendations are advice that, if they don’t help you give birth to twins, will give increased chances to become a mother in general:

Lifestyle - future mom should live on a positive wave, forgetting about smoking and the existence of alcohol.
spring - since ancient times, people believed that with the awakening of nature, human strength also awakens. Will improve hormonal background, the woman’s body will be renewed.
Having given birth to your first child, forget about contraceptives and be sure to feed him breast milk.
nutrition - include in your menu foods that have a positive effect on the ovaries. Typically these include foods from the dairy department, walnuts, sweet potatoes, eggs and yams.
folic acid - start taking it approximately 3 months before trying to conceive. It also affects the functioning of the ovaries, increasing the chances.
A little weight won't hurt - it's good for a woman to have a figure with pleasant curves. How to conceive twins or twins naturally, it’s better to forget about diets and not exhaust yourself with exercise. More often than not, twins are born to mature mothers whose figures have acquired feminine contours.
age - more often twins are born to older women. By the age of 30 3%, by 40 - 6%.

Now you know how to conceive twins!

Cases when not one, but two or more babies settle in a mother’s belly do not occur very often - 1.5-2.5% of all pregnancies. How does this work? How is multiple pregnancy different? Is it possible to plan for twins? Our expert - Anna Romanovna PASTUKHOVA, an obstetrician-gynecologist at the Zdravitsa family medicine centers, answers all questions.

What are the chances of getting pregnant with twins?

First, some statistics. As we have already mentioned, this amazing phenomenon occurs in 1.5-2.5% of pregnancies observed in European countries. It is believed that the appearance of twins, triplets and twins is genetically determined - more often they are born in families where one or both parents were born as a result of multiple pregnancies. However, there are other reasons, including .

The birth of twins occurs with a frequency of geometric progression; obstetricians even have a special formula: for 87 births there is one twin, for 87 twins there is one triplet, for 87 triplets there is one quadruplet, etc. True, today this formula needs correction - multiple pregnancies have become more and more common.

Identical or identical twins are less common, with an average of 1 in 250 births.

Most often, multiple pregnancies occur in Africa, least often in Asian countries.

Types of multiple pregnancy

Let's start with a well-known fact. There are two types of twins: identical or monozygotic and fraternal (they are also called dizygotic).

Monozygotic twins result from the division of one egg fertilized by one sperm. They surprise everyone with their striking similarities.

Fraternal twins are the result of the fertilization of several eggs by several sperm. They can be either the same or different sexes, often differ in character and are not always similar in appearance.

Expert commentary

Multiple pregnancy is a pregnancy when not one fetus develops in the mother's body, but several at once. In medicine, a distinction is made between identical and fraternal twins (triplets, etc.). Identical twins are always the same sex, have the same blood type, and look very similar. Fraternal twins have phenotypic differences (eye color, facial features), they can be either identical or different group blood. Fraternal twins can be of different sexes.

How are identical twins made?

To be honest, we have no idea! The reasons why, instead of a single baby, two (three, four) appear from one egg and one sperm are not really known - it’s a miracle, and that’s all. The mechanism of the appearance of monozygotic twins, however, is described in sufficient detail. Everything begins as if nothing had happened: one egg, one sperm, meeting, fertilization... Then the resulting zygote begins to divide, grow and, at some point, under the influence of not entirely clear factors, suddenly splits into two or more parts, each from which it begins to live its own life.

Expert commentary

The development of identical twins occurs when one sperm fertilizes one egg, during the process of separation ovum into two, three or four parts at different stages of its development. In this case, each part develops as a separate organism. It is assumed that such separation can occur when implantation (attachment) of the fertilized egg is delayed due to oxygen deficiency. The occurrence of identical twins is also associated with the fertilization of an egg that had two or more nuclei.

Do twins interfere with each other?

It is very important at what point the splitting of the egg occurs, since further development depends on this. intrauterine development twins.

There are 3 options for the development of monozygotic twins

The separation of the fertilized egg occurred in the first five days after fertilization. In this case, both future babies begin to develop completely independently, each “grows” its own placenta and . Until recently, it was believed that this development was characteristic exclusively of fraternal twins and identical twins in such cases were mistakenly identified as dizygotic (maybe this is what happened with the Olsen sisters?)

The zygote split approximately 5-8 days after fertilization. By this time external membrane has already begun to take shape: remains common among babies, but the inner membrane of the fetus (amnion) develops in each individual. If babies have a common placenta, then one child can suppress the other - their competition begins from conception.

Separation occurred on day 8 or later (1% of all monozygotic twins). At this time, the amniotic sac is already beginning to form, so the separated embryos will grow in the common amnion and common fetal fluid. This situation is not considered the most favorable; there is a risk that children each other.

The life of fraternal twins in the womb is organized with great comfort: each of them develops their own personal placenta (sometimes they are fused with walls), which means that the babies do not need to seriously compete for a place “in the sun.”

So, if the embryos have different placentas, then most likely they are fraternal, and if the babies “settled” with a common placenta, then these are identical twins who will be born similar as... twins.

Expert commentary

The following types of multiple pregnancy are distinguished:

Monochorionic monoamniotic twins, when there is a common placenta and there is no septum between the twins. It's always identical twins

Monochorionic diamniotic twins, when there is a common placenta and septum, i.e. each fetus has its own amniotic sac

Dichorionic diamniotic twins, when each fetus has its own placenta and amniotic sac.

How do you get fraternal twins?

Non-identical twins develop from two or more fertilized eggs. How does this happen? The most common reason for this is the so-called “multiple ovulations,” when several mature eggs are released from one or both ovaries at once. The reasons for this phenomenon may be different: genetic predisposition, artificial stimulation ovaries, first cycle after discontinuation of hormonal contraceptives.

Do you know that....

The difference in the time of conception of fraternal twins can be from several hours to several days.

In very rare cases, already existing pregnancy new one is added. As a rule, after fertilization and implantation of the fertilized egg, ovulation is immediately blocked. If due to hormonal imbalance this mechanism does not work immediately; it is added to the older child in utero younger brother or little sister.

Twins are one face and body, like two peas in a pod. They are very close spiritually and physically. Often such people get sick at the same time, even if they are at a distance. Twins feel each other. The same cannot be said about twins. They can be completely different, there are even cases when children were born from different fathers during one pregnancy.

How do you get twins and twins?

The appearance of two babies in the womb at once does not mean that they will be exactly the same. There are three options for the development of events here. In medical practice they are characterized as follows.

Identical (identical). Such children are obtained from one egg, which, for reasons unknown to science, is divided into 2, and in rare cases, into 3 parts. Children have the same gender, set of chromosomes, blood type and often identical fingerprints. In 25% of cases, the features of monozygotic twins are a mirror image of each other, which is especially evident in moles.
Semi-identical (polar). This is a very rare case, as a result of which children are born with a 75% match of the genotype. They combine the characteristics of identical twins and twins. Such babies are born as a result of fertilization of one egg by two different sperm and its polar body. Moreover, the offspring can be either single- or heterosexual.
Fraternal (dizygotic). Such babies are produced due to the fertilization of different eggs. Their set of genes coincides by 50%. Twins can look completely different and have different genders.

Here are the main differences between twins and twins. But if you delve into the details, you can find quite a few more inconsistencies.

Identical embryos coexist in the womb different conditions. It happens that they are formed in the same amniotic sac and with a common placenta. It is possible that the embryos have their own bubble, but a common placenta. And the third case is that each baby has its own placenta and amniotic sac.

When a dizygotic pregnancy occurs, the fetuses have a separate placenta and amniotic sac.

Features of monozygotic twins

It is impossible to plan to conceive identical twins. In this case, nature is in charge. Heredity and parental age are not fundamental factors. Identical babies are born quite rarely - about 1 time in 3.5-4 thousand births.

These children have the same appearance. Even close relatives often confuse them when the children are too young. Identity lies not only in the same eye and hair color, but also in the peculiarities of the body structure and the location of the teeth.

Another fact that is relevant for twins is that organ and tissue transplants between them are 100% successful. Scientific studies have shown that monozygotic children have almost identical brain electrical activity curves.

Identical twins are believed to have a special blood connection. They not only think alike, but also often love the same people. It is worth assuming that their tastes in cinema, music and other areas of art completely coincide.

Features of dizygotic pregnancy

Twins, a boy and a girl, are not uncommon. If you're lucky, they'll add one, two, or even more babies. The world knows of cases where a woman gave birth to 11 dizygotic twins at one time. But, unfortunately, none of them survived. The story of the birth of eight babies at once is more successful - each of them turned out to be healthy.

The likelihood of such a pregnancy increases due to hormonal therapy. It is prescribed for the treatment of infertility. As a result, the amount of follicle-stimulating hormone is quite high, which leads to the production and maturation of several follicles at once. Usually the eggs are released simultaneously and, under favorable conditions, are fertilized.

IVF also increases the likelihood of multiple pregnancies. Several zygotes are transplanted into patients at once. Not uncommon cases, when a lot of material takes root, so the doctor recommends removing part of it. This procedure ensures normal development embryos.

Experts note that women after 35 years are more likely to give birth to twins. A similar pregnancy you can plan. If there have been cases of dizygotic twins in the family, then the chances of having double offspring immediately increase.

Twins are born much more often than identical twins. This happens 1 time in 90 births. But triplets are a rarer occurrence, occurring once in 8,000 births.

How to diagnose twins and twins

This process is quite exciting for future parents. It has the following features.

Diagnosis occurs using ultrasound. In the early stages, a specialist can only identify larger size uterus than in a normal pregnancy, and two beating hearts.
From 4-5 weeks, the doctor will accurately determine the number of embryos. However, whether it will be twins or twins, the parents will find out only after the birth.
Expectant mother and father can be confident that they are expecting dizygotic twins if they have undergone IVF.

Features of education

In this case, parents have a double burden, because raising children of the same age who are also so similar in appearance is quite difficult.

Often one of the children becomes the leader. He is the instigator of various pranks and constantly provokes his brother or sister to do bad things. The second child becomes a follower and carries out all the “assignments”. Mom and dad need to explain to their children that they are equal to each other. It is important to distribute parental care and care evenly so that one of the kids does not feel deprived.

Don't compare children. Each of them is an individual with his own character and ambitions. Even if one of the twins has some kind of defect or deficiency, you should not focus on this. In addition, it is necessary to find some distinctive ability or talent in the child and develop it. Call children by name as often as possible, and try not to generalize, especially if one of the twins did a bad thing.

The parents' task is also social adaptation kids. You shouldn’t limit their social circle to just each other. Take the kids out for a walk where they will interact with different kids. When the twins grow up a little, gradually develop their independence from each other. To do this, occasionally organize separate trips to the playground or to the cinema.

A common mistake many parents make is buying identical clothes and gifts for twins. In infancy, this is allowed, but with age it is worth abandoning such an idea. Give kids the right to choose. For a birthday, order not one large cake, but two small ones, so that each child has his own celebration.

Twins and twins are different phenomena. The following information will not only confirm this, but may also be new to you.

In ancient times, it was believed that the birth of two identical children was the result of the intervention of evil spirits.
Exist special diets, which supposedly allow you to conceive twins. But their effectiveness has not been proven.
Twins are like children of the same parents, born in different time. Not only can they have different sexes, but also different fathers and even skin color.
Siamese twins- These are identical twins whose division began at a late stage. Because of this, they are born fused. In more successful cases, children have one area of skin between them, and in very complex cases, the spine.
Dizygotic twins are born at different rates on different continents. The leaders in this case are African countries, and Asia, in particular Japan, closes the list. Europe is characterized by average indicators.
Even if identical twins are raised in different environments and are far from each other, they remain similar, have the same development and suffer the same diseases.
Adult dizygotic twins often grow apart from each other. They are realized in different spheres of life and communicate with different people. But identical twins, on the contrary, are getting closer every year.

Although twins and twins are forced to live together until they grow up, parents still need to develop them as individuals. You should not identify twins, especially identical ones, even despite their external similarity.

comparison table

To make it clearer to our readers how twins differ from twins, we have compiled a comparative table.

Index	Identical (identical, monozygotic)	Polar (semi-identical)	Fraternal (dizygotic)
Features of fertilization	The result of the division of one zygote	Fertilization of one egg and its undead polar body	Fertilization of two or more eggs that mature at the same time
Genotype matches	100%	75%	By 50%
Blood type	Same	Same	Same or different
Floor	Same-sex	Same-sex or different-sex	Same-sex or different-sex
Appearance	Absolute similarity, in 25% of cases mirror appearance	Children are very similar, but there may be minor differences	Children can be completely different, even have different colour skin
Spiritual intimacy	Close all their lives, feel each other from a distance	Close enough	Some twins grow apart as they age
Probability of pregnancy	1 out of 3500-4000	An extremely rare occurrence	1 of 90

The birth of twins is quite rare, as twins make up only 2% of newborns. When triplets are born, it becomes known throughout the city, since triplets are born even less often and already account for 2% of twins born.

Multiple pregnancies are different. Not all children born as a result of such a pregnancy are alike. There are identical and fraternal twins. Eternal twins are as similar to each other as any brother and sister. Despite the fact that they develop in the uterus at the same time, the difference in the time of their conception can be from several hours to several days. These twins develop from two fertilized eggs. They can be either the same or different gender. Identical twins are produced when a single egg is fertilized by one sperm, and as a result of division, independent embryos are subsequently formed.

So far, doctors cannot determine the reason for this behavior of the germ cell. Identical twins look so much alike that it's sometimes hard to tell them apart. own mother. Such twins are 5 times less common than fraternal twins, and boys predominate among them.

A special phenomenon is Siamese twins, who share some common organs or body parts. The reason for this phenomenon is that the splitting of the embryo into independent forms occurs later than during the birth of ordinary twins, at a time when the embryo is already partially formed. Siamese twins are extremely rare. They are born once in 10 million births.

Twin embryos are the most capricious

Rare cases of the birth of twins are partly due to the fact that not all of them take root in the very first days after birth. For a woman, this goes unnoticed, and she does not even realize that she was “slightly” pregnant with twins. It has been established that only one in 10 cases of conception ends normal pregnancy and leads to childbirth. It is impossible to plan the birth of twins. But there are completely objective reasons that increase the likelihood of having two or more babies at the same time. Moreover, this only applies to fraternal twins, because the probability of having identical twins is always constant. On average, it is 3 cases per 1000 pregnancies.

Chances of conceiving fraternal twins

So, the age of the woman is of paramount importance. The older you are, the more hormones your body produces. And hormones stimulate the maturation of the egg, therefore, with an increase in the number of hormones, the likelihood of several eggs maturing at once, ready for fertilization, increases. Therefore, for women aged 35-39 years, there is a real chance of conceiving fraternal twins.

Hormone production is affected not only by age, but also by duration daylight hours. The most best time for conceiving twins - spring, when the day lengthens and the sun begins to gently warm.

Heredity is of great importance. So, if there are already twins in the family, then the probability of giving birth to another pair is quite high, but it decreases with the distance in time of the generation of twins.

The ability to conceive twins is passed on only through the female line. Men can pass it on to their daughters, but there is no noticeable frequency of twins in the offspring of men themselves.

There is also an influence of duration on the conception of twins. Women who have the greatest ability to give birth to twins menstrual cycle very short - 20-21 days, as well as women with abnormalities in the development of the uterus, for example, in the presence of a septum in the uterine cavity or with a bicornuate, as if forked, uterus.

And finally, twins and even triplets are quite often born through artificial insemination. This also occurs due to the use of hormonal drugs that stimulate egg maturation and ovulation. The appearance of two or three children in a family after many years is not such a rare occurrence.

There is an inexplicable pattern of more frequent births of twins during various social upheavals and wars. Maybe nature cares so much about preserving man on earth.

Nina Bashkirova, “Planning a Child”