When an embryo divides into twins. How do you get twins and twins?

Twins- These are children of different identities. Such a pregnancy occurs when two eggs are simultaneously fertilized by different sperm. Each fetus is formed in a separate placenta.

Twins can be either similar or completely different. The same goes for gender.

Scientists have been able to establish that the predisposition to having twins is transmitted genetically through the maternal line.

The chance of conceiving twins is 3 times higher than conceiving twins. It has also been noted that twins are more often born to older women.

At 20-30 years old the expectant mother has 3% chance conceive twins naturally. A at the age of 30-40 years these chances increase to 6% .

With each subsequent pregnancy, the possibility of conceiving twins also increases, because the birth of a child is accompanied in most cases. And women who are slightly overweight are much more likely to become pregnant with twins.

In addition, according to studies, mothers who breastfeed and become pregnant during this period are more likely to conceive twins.

How can you conceive twins?

It is easiest for Middle Easterners and Africans to conceive twins. Geographical factors also play an important role in creating twins.

For example, in the village of Kopan (Carpathians), 54 pairs of fraternal children were born over 50 years. The villagers say that this is due to the healing water source that the village has. It is he who creates favorable conditions for the birth of twins.

Therefore, many people who want to become doubly happy parents come to this source. And some couples managed to conceive twins after a trip to this magical place.

In the Rostov region, in the village of Denisovka, amazing phenomena were also recorded. There for every 500 people there are 19 pairs of twins. This is influenced by fertile soil.

Local residents say they know how to get pregnant with twins. In their opinion, even after staying in this village, the husband and wife will be able to conceive two children at the same time.

Artificial insemination and twins

Doctors also know about the secrets of conceiving children of different identities. The method, like nothing else, contributes to their birth.

After all, thanks to this method Several eggs are fertilized at the same time, which are immediately transplanted into the woman. The likelihood that in this case two babies will be born is very high.

If you really want to give birth to twins, but IVF is not the initial method for you,... He will tell you how to make your dream come true.

Before going to the doctor Find out all the information about your family, take medical histories (your own and your husband’s), and then go for qualified advice.

How to conceive twin girls?

When conceiving twin girls, the position in which you make love is of great importance. In this case, it is better to refuse deep penetration. The missionary position is more suitable.

Also have a special diet, which increases the chances of conceiving girls. Your daily diet should include sugar, spices, aromatic herbs, and jams. It is recommended to avoid products containing caffeine and salty foods.

Another method is built on the theory of youthful blood. It is generally accepted that it is this factor that determines the gender of the child.

Because the A woman's blood is renewed every three years, and a man's - every four, it is necessary to carry out a countdown that starts from the last major blood loss: surgery, abortion, childbirth.

Depending on whose blood turns out to be younger at the time of conception, you will be able to determine the gender of the unborn baby.

How to conceive twin boys?

1. Guided by desire to become parents of twin boys, you can use positions with deep penetration, which are good because it is easier for Y-sperm to have a short distance to the uterus and they live less than their X-rivals. There is information that the favorable penetration of these sperm is much more effective after a woman’s orgasm, since substances are released that contribute to the vitality of Y-sperm.
2. Have sex before ovulation. It is necessary to guess the timing of this process in the female body due to the short lifespan of Y-sperm. This will increase their chances of getting to a mature egg faster than their counterparts.
3. Stick to it special diet, which provides for the exclusion from the diet of dairy drinks, crabs, sauces, pastries, bread, waffles, green salad, legumes, raw, nuts, etc.

   Instead, actively consume fruit juices, with soda, all varieties and sausages, egg whites, biscuits, cookies, semolina, all fruits and dried fruits (,), black. Salt your food more, eat canned food and dishes prepared with yeast more often.

Certainly, all these means give a very small percentage of probability conception of male twins. But in the fight for your dream, as they say, all methods are good.

Go towards your goal and do everything to to achieve what you want. Believe me, your efforts will be adequately rewarded.

Even if not twins, but one child. But the happiness of motherhood and fatherhood lies not in the number of children, but in how well you can cope with a responsible parental role.

Expert commentary

The human body is designed to bear and give birth to only one child. No matter how strange it may seem, but from a medical point of view, multiple pregnancy is considered an anomaly.

The process of conception involves the participation of only one egg and a single sperm. When two eggs are produced, it becomes possible to become pregnant with twins. In this case, children can be of different sexes and different blood groups.

If a single fertilized egg splits exactly in half, copying the genetic code, the result is identical twins. The copying mechanism is known, the reasons are not clear. One way or another, the appearance of monozygotic twins does not depend on the fact of conception.

The splitting of the egg occurs later. If for some reason it occurs later than the zygote stage, the result is conjoined twins, first described in Thailand - Siamese.

Reasons for the formation of multiple eggs

A woman's cycle normally involves the release of only one egg. She appears and turns on the second phase mechanism. This happens throughout a woman’s childbearing years. The greater the supply of follicles, the longer the menstrual period lasts.

Hormonal changes that promote the formation of multiple eggs:

• taking hormonal contraceptives for three months and then discontinuing them;
• drug stimulation of ovulation;
• heredity;
• duplication of the uterus in the embryonic period.

Rebound effect

This is the formation of an egg after discontinuation of a hormonal drug. When taking hormonal contraceptives, the ovaries “rest” for three months. The hormonal cycle is supported artificially.

The ovaries function in turn. In one month, ovulation occurs in the left, in another - in the right. After the break, both appendages are “triggered.” At the same time, two full-fledged eggs are obtained.

The rebound effect is a phenomenon, although planned, but uncontrollable. Its appearance is spontaneous.

Ovulation stimulation

Drug stimulation leads to the maturation of several follicles at the same time. At ovulation, two or three eggs are released. All or one is fertilized.

Hereditary factor

The predisposition to conceiving fraternal twins is inherited through the female line. Typically within a generation. If the grandmother gave birth to twins, the granddaughter has every chance. In the absence of abortions. Forced termination of pregnancy, regardless of twins or one fetus, destroys the original genetic setting.

Abnormalities of the uterus

Complete doubling, or the presence of a septum in the organ, leads to increased egg production. They are generated on demand. If there is only one uterus, one egg is required.

Additional factors contributing to the conception of twins

Conditions that are independent of the state of a woman’s body, but influence it, are considered additional factors.

Climatic factor

Under certain conditions: length of daylight, humidity and natural radioactive background, the work of the appendages is activated. Several eggs are produced in the ovaries. Increased numbers have been observed in some areas.

A trip to such places for one or two days does not guarantee the birth of twins. The formation of the egg occurs within two weeks.

Age factor

Women over 33-35 years old experience a hormonal surge. The synthesis of follicle-stimulating hormone increases significantly.

This is how several eggs are formed, but it is not a fact that each of them, after fertilization, turns into an embryo. Implantation depends on the woman’s health condition.

With multiple ovulation, only one child may appear. Or none.

IVF as a family planning tool

During in vitro fertilization, after ovarian stimulation, receive several eggs. Four to six are fertilized. It's different in different countries.

Taking root either all embryos or two. Under any conditions, all other children are destroyed except two.

That's why IVF can guarantee the birth of fraternal twins, and may not guarantee anything. There is no certainty that fertilized eggs will remain in the uterus during artificial replantation.

The birth of a child is an unusual, enchanting moment. The whole life of a young mother begins to revolve around a small miracle that has come into the world. And if a woman is given two (or more) babies, then her happiness increases.

The birth of twins brings with it excitement, upcoming caregiving chores, sleepless nights, but the moment of the birth of children is filled with happiness.

Types of twins

If a woman is diagnosed, she will give birth to twins. Children can be either absolutely identical or not very similar at all, and even of different sexes. It all depends on the egg. Depending on this, twins are divided into:

• identical (monozygous);
• non-identical (dizygotic).

Identical twins

The birth of two absolutely identical children remains a mystery to humanity. Why at the initial stage the egg begins to divide and create identical embryos remains unknown.

Monozygotic twins are the result of fertilization of one egg by one sperm. The resulting diploid cell begins to divide, resulting in the formation of independent embryos. Most often there are two, but there may be more. The similarity of future babies from such a pregnancy is determined by the time of separation of the embryos. If it occurs in the first 5 days, then the embryos each have their own placenta and amniotic sac. In this case, there will be minor differences in the appearance of future babies. If separation occurs after the fifth day, then the embryos have one common placenta and their similarity to each other becomes absolute.

Fun fact: monozygotic twins have identical fingerprints in most cases.

The reasons why a zygote divides into two or more identical embryos have not yet been studied. The probability of having identical babies is 3 in 1000 and does not depend on heredity.

Fraternal twins

The conception of such twins results from the fertilization of two eggs by different sperm. During intrauterine development, each embryo has its own placenta and develops independently of the other. Dizygotic twins can be either same-sex or opposite-sex. They will have the same external resemblance as brothers and sisters born from a normal singleton pregnancy.

Fraternal twins can be conceived within hours, or perhaps even days, of each other.

Features of the development of dizygotic twins

The following facts are known about born fraternal twins:

• their genes coincide by about 40-50%;
• each embryo has its own placenta and its own amniotic fluid;
• born babies can be either same-sex or different-sex;
• children may have different blood types;
• the likelihood of their occurrence increases in women over 35 years of age;
• as a result of the IVF procedure, twins most often appear, since the woman is given several

Is it possible to plan the birth of twins?

The birth of a child is an unusual, enchanting feeling that arises in a young mother who has given birth to a child. And birth contributes even more to the feeling of happiness. However, it is impossible to schedule their appearance.

When an egg is fertilized, information is immediately stored both about the future baby and about what kind of pregnancy it will be - singleton or multiple, so it is impossible to influence this process naturally. You can only find out the factors that increase the likelihood of twins.

These factors include:

• pregnancy at the age of 35-39 years;
• the presence of twins in a generation (the appearance of identical twins is not associated with hereditary factors. To date, it has not been studied why and under what conditions the egg begins to divide);
• short menstrual cycle (20-21 days) - with this cycle the likelihood of several eggs maturing increases;
• infertility treatment. In the treatment of infertility, hormonal drugs are used that stimulate ovulation, which can result in multiple pregnancies;
• artificial insemination - in vitro, often leads to the birth of twins or even more babies.

Differences between twins and twins

We can summarize how identical twins differ from fraternal twins. Let's consider the characteristic features that babies born during a multiple pregnancy will have.

Identical twins:

• Children have an identical similarity, but in some moments it can be mirrored. For example, a mirror image of existing moles.
• In addition to external similarity, the same physique, hair structure, teeth arrangement, voice timbre, and even thoughts are quite similar.
• They have the same blood type and most often similar fingerprints.
• Always same-sex, they are also called natural clones.
• It is impossible to plan the birth of monozygotic twins.

Fraternal twins:

• There are both same-sex and heterosexual.
• May have different blood types.
• External similarity is superficial.

As you can see, there are no similarities between identical and fraternal twins, only one name - “twins”. At the same time, it is common for people to call identical babies twins, and fraternal babies - twins, triplets, etc. Differences between them begin to appear from the moment of conception.

Conclusion

The appearance of two or more babies as a result of one pregnancy brings with it increased attention from people around them to children. At the same time, fraternal twins look like an ordinary brother and sister (2 sisters or 2 brothers), so they do not attract close attention.

Identical twins always arouse interest in society. Most likely, this is due to the rarity of such a phenomenon. Therefore, seeing two absolutely identical people, a passerby will definitely fix his gaze on them.

At the same time, you need to know that multiple pregnancies are observed under special control, since the body experiences a greater load than during a normal pregnancy. The expectant mother should be attentive to her health. Therefore, in order to give birth to healthy twins, you need to listen to the doctor’s recommendations, then the moment of meeting your babies will be filled only with positive things.

Identical twins or fraternal twins is something you hear when people talk about twins and twins. What does the number of eggs and twins have to do with it? We suggest at the everyday level, without delving into the exact definitions, to figure out what it is when people say fraternal or identical twins. We’ll also briefly touch on a couple more difficult points. Let’s connect “eggs” and zygotes plus pregnancy. We will deal with different and identical twins using everyday concepts and a school biology textbook.

Identical twins and fraternal twins - the basics

To better understand what fraternal or identical twins are
Let's remember some basics. Let's start with the fetus and multiple pregnancies.

Fetus- this is generally the result of pregnancy of the female body, in our case the mother. There are different stages of fetal development. Sometimes, based on these stages, the fetus is called an embryo or fetus. It's always about the same thing, about the result of pregnancy, i.e. about the fact that inside the mother’s body lives and develops, and then, in a positive result, should be born in the form of a child, in our case, twins.

Egg is a reproductive cell that develops in the female body. When merging with a male reproductive cell (sperm), the egg develops into a fetus through the process of splitting the egg into smaller other cells. The ovum is similar in structure and appearance to an egg, which is where it gets its name.

Multiple pregnancy

Pregnancy can be singleton or multiple
. Singleton - one child will be born, multiple pregnancy - two or more twin children may appear.

Twins(twins), triplets, etc. - these are numerical designations of the number of children born during a multiple pregnancy. Twins (twins) – two children, triplets – three, etc. However, they are all called twins, even if they were born in a different zodiac sign. They can also be identical or fraternal twins.

Twins- children born during one pregnancy and resulting from one birth to one mother. At the everyday level, everything is simple. Twins are different children from the same mother, after the same birth, and twins are identical children under the same circumstances. But in essence, it doesn’t matter whether they are similar or not, it doesn’t matter what they are called twins, twins or twins - they are still twins, you just need to remember. Twins are children born as a result of multiple pregnancy.

Identical and fraternal twins or twins

So, we know that children born as a result of multiple pregnancies can be identical or fraternal twins or, simply put, twins. And there is another option when the so-called mirror twins appear.

Identical twins (twins)

Identical twins or identical twins are children born as a result of multiple pregnancy when one egg is fertilized by one male reproductive cell, which leads to the appearance and development of two or more fetuses. The children turn out almost identical, i.e. identical.

How are identical twins made?

Let's outline how identical twins are created. In fact, any fertilized egg (it can be called a zygote) during intrauterine development is divided into two or more parts. This is how children become genetic copies of each other, i.e. identical. Roughly speaking, this is how natural cloning occurs. It is to this process that we owe the appearance of twins.

The division of a fertilized egg is directly responsible for how identical twins are produced .

• If the division occurs before day 3, inclusive, after fertilization, then the result is dichorionic diamniotic twins, which is very similar to fraternal twins.
• If the division is between 4 and 8 days after fertilization, the result is monochorionic diamniotic twins.
• If on the 9th or 10th day - monochorionic monoamniotic twins.
• If between the 13th and 15th day, such separation will not be complete and the result will be monochorionic monoamniotic conjoined twins - Siamese twins.

What “chorial” and “amnion” mean will be discussed below.

Mirror twins are identical

By the way, identical twins can be mirror twins
, i.e. in one of them the location or appearance of some objects of the body may be the same as if the other looked in a mirror. For example, a mole on different parts of the body, one on the right, and the other on the left. One may be right-handed and the other left-handed. Identical mirror twins can only be monozygotic (homozygous) and occur in 25% of twin births. They may be very similar in fingerprints, but still differ in small details. Their blood type is the same.

Fraternal twins (twins)

Fraternal twins or twins are children born as a result of multiple pregnancy when two or more different eggs are fertilized by two or more different male reproductive cells, which also led to the appearance and development of two or more fetuses.

Simply put, each egg has its own sperm. Children can turn out different in everything. A striking example is twins, a boy and a girl, also known as royal twins. In this case, fraternal twins are always dichorionic diamniotic twins.

Identical twins and fraternal twins: "eggs" plus zygotes and pregnancy

Here we will actually make an attempt to combine medical, biological and everyday terms into one whole, so that we no longer get confused and understand exactly what we are being told about the same thing, just in different words. This is all about identical and fraternal twins.

All twins, twins, triplets, etc., as well as twins and twins, are twins in the biological sense. However, there are established terms and concepts in which the word “twins” is used.

In medical terminology, when describing pregnancy, twins are distinguished by the placenta (one or more) and by the number, presence of septa in one amniotic sac (one or more). There is a separate article on this subject: monochorionic diamniotic twins or monochorionic monoamniotic twins or diamniotic diamniotic twins - WHAT IS THIS or WHO IS THIS??? In it we tried to explain as simply as possible what it is. At first glance, it seems that this is a repetition of everything said above, and this seems correct. However, there are still those who are confused and think that it is all about different twins. It’s written there just for them, let them read it.

When describing the birth or appearance of twins, the differences between twins are described in the number of eggs involved in their appearance. There will also be words from the field of genetics - zygotes, genes, chromosomes.

At the everyday level, twins are always different, and twins are always the same, everything is simple here.

Fraternal twins = dizygotic twins = dichorionic diamniotic twins

Fraternal twins or twins are always and definitely dizygotic (heterozygous) and dichorionic diamniotic twins. These are twins in the everyday sense. In fact, these are two different children; in everyday life they would be called twins.

They were the result of a multiple pregnancy and will develop as two different children. The children will resemble each other like close relatives and nothing more. Here we started using “different” hetero, di and monozygotes. In the article monozygotic twins and dizygotic twins - WHAT IS IT, you can learn in detail about them and their connection with twins.

It should also be noted that, unlike identical twins, for fraternal twins it does not matter when the separation occurred, because it was the default at the time of conception. The only option is for the placentas to grow together. Then the dichorionic diamniotic twins “become similar” to the monochorionic diamniotic twins, but they are still two different placentas.

Identical twins = monozygotic twins

Identical twins or twins are always monozygotic, also known as homozygous twins, i.e. as a result of a multiple pregnancy, children of the same sex and blood type were absolutely similar to each other. In everyday life they are usually called twins. And then the differences begin, although at the everyday level they are still always twins. Identical twins (twins) are distinguished by:

• monochorionic diamniotic, i.e. fetuses (embryos) are connected in the womb to the mother by one placenta and each has its own amnion (amniotic sac). In fact, in the common amnion there is a partition separating the fetuses, and it turns out to be like their own apartment for each in a common house. Then identical twins, like fetuses, develop separately from each other. The probability of occurrence is 70-80% of all identical ones. Division occurred between 4 and 8 days after fertilization. If division occurs between the 13th and 15th day after fertilization, it will not be complete and the fruits (embryos) will grow together - a very difficult case.
• monochorionic monoamniotic, i.e. Fetuses share one placenta and one common amniotic sac. This means that the fruits are not separated by a septum in the amniotic sac, and develop together. This is a very dangerous option for the development of identical twins. There is a possibility of having conjoined twins. Chance of occurrence is 1% of all identical ones. Division occurred after the 9th day, inclusive, after fertilization.
• dichorionic diamniotic, everything is like fraternal twins. The probability of occurrence is 20-30% of all identical ones. Division occurred up to 3 days, inclusive, after fertilization.

Natalia Danilovich

We all know that a boy and a girl (fraternal twins) can only be fraternal twins. They can never be identical. And in the vast majority of cases, in fact, a boy and a girl are only twins. And yet there are very, very, very rare cases where parents of twins can actually say: “My boy and girl are opposite-sex identical twins.” And you know, there are three different explanations for this event!

Often the question “Are you having twins?” For the parents of the royal couple, babies in all blue and pink leads to ambiguous thoughts that there are just a little crazy people nearby, even when they are interested in this issue with completely good intentions.

Let's look at everything in order and remember the main points from biology from school.

Monozygotic or identical twins are the result of one fertilized egg splitting into two zygotes early in pregnancy. Twins have an almost very similar set of chromosomes.

Dizygotic twins, or colloquially twins, are produced from two different fertilized eggs. Twins have completely different chromosomes, just like normal single-born siblings. With the exception of general pregnancy and childbirth.

Identical (monozygotic) twins are always the same sex because they come from the same zygote, which may contain either male (XY) or female (XX) sex chromosomes.

That's why...

In the vast majority of cases, a boy and a girl can only be fraternal twins.

Nevertheless....

1. Sometimes it’s a matter of chromosomes

Identical opposite-sex twins
For some unexplained reason, in very extremely rare cases (about 1 in 2500 births), in the case of a male (XY) fetus, one of the twins loses the Y chromosome and continues to develop as a girl with only the (XO) chromosome.

This extremely rare phenomenon unfortunately belongs to chromosomal disorders and is called Turner syndrome. A twin girl with Turner syndrome will have distinctive features such as short stature, low-set ears, abnormal bone development, delayed or absent puberty, and other possible features.

Because Turner syndrome is a chromosomal disorder, there is no cure. However, treatment still exists. Growth hormone can help a child grow bigger. In vitro fertilization can help a woman with Turner syndrome become pregnant. Hormone therapy (estrogens) can help with the onset of puberty.

Scientists are also familiar with cases of identical twins of opposite sexes caused by Klinefelter syndrome. With it, the child has one extra X chromosome, less often there are several extra X chromosomes: XXY; XYY; XXXY; XYYY; XXYY; XXXXY; XXXYY. The most common is Klinefelter syndrome (XXY). Normally, the normal set of sex chromosomes in men is described as XY.

Parents of identical opposite-sex twins with such characteristics may have to constantly delve into the lesson from school biology described above. Explain to everyone around the chromosomal differences between men and women. Walking through the cactus garden out of wonder at their story about their twins. Not to mention encounters with various doctors, procedures, tests and prescriptions.

These situations are so extremely rare (less than 10 cases can be found). Therefore, we can confidently assume that in 99.9% of cases, a boy and a girl will be opposite-sex fraternal twins.

2. Another type of twins

Semi-identical twins
Everything gets more interesting here. There is an unusual way for twins to appear, when fertilization of an egg is carried out by several sperm or the egg divides before fertilization, which can lead to the conception of male and female children.

In this case, the twins will be formally identical, because their genotypes will already be different. This type of twins is currently called semi-identical twins. They will share 75% of their genetic markers.

This is a very interesting option; various studies have been conducted on it, which prove that subsequent division of a twice-fertilized egg and the birth of healthy children are possible. And with possible differences between the sexes, neither a girl nor a boy (if we consider the norm, and not chromosomal abnormalities among the sex chromosomes) will suffer from anything.

Interesting? There is one more exception, when identical twins can be opposite sexes....

3. Gender reassignment surgery for one of the twins...

Thus, you see, becoming parents of identical twins of opposite sexes - a boy and a girl - is not completely impossible and simply incredible. But this possibility is not always worth the extra pleasure from unnecessary communication with doctors, physical characteristics on the part of your beloved children, your emotions and rushed attention to you.

Pregnancy and the birth of a child are always a miracle, an extraordinary gift. And when two are expected at once? What about three? It is not for nothing that twins and their parents so attract the attention of others - sometimes enthusiastic, sometimes sympathetic. This is truly a rare occurrence. Twins make up about 2% of all births, and triplets make up only 2% of all twins. But before you become the happy owner of a double stroller, you have to go through a long journey of carrying a special, “non-standard” pregnancy.

Children born as a result of multiple pregnancies are called twins. In addition, you can often hear the word “twins,” which is colloquially used to describe “dissimilar” twins.

How does this work?

Twins there are two types:
– Dizygotic (two-egg, non-identical) Twins develop from two fertilized eggs. In some cases, the simultaneous maturation of two or more eggs occurs in one or both ovaries. A third method of origin of fraternal twins is possible: fertilization of two or more eggs matured in one follicle. Interestingly, sometimes the difference between the time of conception of dizygotic twins can be from several hours to several days. Fraternal twins are no more genetically similar than ordinary siblings, and are about the same frequency of being the same sex or of different sexes.
– Monozygotic (identical) Twins are produced when a single egg is fertilized by one sperm. Then the resulting zygote begins to divide as usual, but with an interesting feature: as a result of division, independent embryos are subsequently formed. The reasons for the development of this process have not yet been precisely established by science due to the complexity of the biochemical mechanisms that regulate cell division. Such twins are almost exact copies of each other, although, of course, there are still minor differences between them. After all, different mutations can occur in the initially identical DNA of each embryo. The second reason for the differences is non-genetic influences, such as characteristics of the areas of the female uterus or the influence of other factors. Monozygotic twins are 5 times less common than dizygotic twins. Among monozygotic twins, boys predominate.

Separate topic - Siamese twins. This is the name given to identical twins who are fused to each other to varying degrees. The supposed reason is the late splitting of the embryo into independent forms. The later this happens, the higher the risk. Siamese twins are extremely rare. They are born once in 10 million births.

Many twin conceptions do not result in birth. For every pair of twins born, there are 10-12 people who had a twin in the womb.

Is it possible to plan the birth of twins?

Naturally - practically not. If pregnancy has already occurred and the woman knows about it, then in any case it is impossible to change the course of events by any means, because in the process of fertilization information about the future child is laid down, including whether there will be one or two.
But some factors still increase the likelihood of conceiving fraternal twins, while the likelihood of having identical twins is not associated with any hereditary or external factors and is constant - on average 3 per 1000 pregnancies, that is, 0.3%.
So, in women aged 35-39 years, the likelihood of such conception increases. The fact is that during the late childbearing period, the concentration of a hormone in the female body increases, which stimulates the maturation of the egg. Thus, several eggs ready for fertilization can mature at the same time. It is also known that the production of this hormone is influenced by the length of daylight hours. Therefore, you are more likely to conceive twins in the spring, when the sun begins to warm up noticeably.

If there were already twins in the family, then the probability of giving birth to fraternal twins is higher, the closer the generation in which this happened. The tendency to give birth to fraternal twins occurs only in women. Men from such families can pass this property on to their daughters, although an increased incidence of twin births is not observed in the offspring of these men themselves.
More often, several eggs mature in women who have a short menstrual cycle - 20-21 days, as well as in women with abnormalities in the development of the uterus, for example, in the presence of a septum in the uterine cavity or a bicornuate uterus (a pathology of the development of the uterus in which the organ is not pear-shaped, but as if bifurcated).

In recent years, hormonal drugs that stimulate egg maturation and ovulation have become widely used to treat infertility and other gynecological diseases. As a result, a long-awaited pregnancy after many years of infertility often turns out to be twins or triplets! Successfully developing technologies of in vitro fertilization (IVF) have also led to the fact that pregnancy with twins or triplets is no longer a rarity. Twins after IVF are always fraternal, often of different sexes, each with their own appearance and character.
The frequency of twin births is significantly higher during various social upheavals and wars.

When can you find out about twins?

Fifteen to twenty years ago, people learned about twins only during childbirth or not earlier than the 20th week of pregnancy. When recognizing a multiple pregnancy, the following signs were taken into account.
The enlargement of the uterus during multiple pregnancy occurs faster than during pregnancy with one fetus, so the size of the uterus does not correspond to the duration of pregnancy. At the same time, the significant volume of the pregnant uterus does not correspond to the small size of the presenting fetal head. In addition, with twins, a deepening of the area of ​​the uterine fundus (saddle-shaped uterus) can be detected, the formation of which is associated with protrusion of the corners of the uterus by large parts of the fetus; as well as a longitudinal depression on the anterior wall of the uterus if the twins are in a longitudinal position, or the presence of a horizontal groove on the anterior wall of the uterus if the twins are in a transverse position. For a long time, it was important for the diagnosis of twins to clearly identify three or more large parts of the fetus in the uterus during an obstetric examination (two heads and one pelvic end or two pelvic ends and one head). Of equal importance was the presence of two distinct heartbeat points in different places of the uterus.