Statistics of the birth of twins in the world. Twins. The optimal time for childbirth. Reasons for the birth of twins

According to various estimates, today in the world there are from 70 to 80 million pairs of twins.

The number of twins born in relation to the total number of newborns in different countries and on different continents is different, but in general the trend is such that it continues to grow. Compared with the 60s, the percentage of twins has increased from 1.18 to 2.78, that is, almost 2.5 times. Much is said about the reasons for this phenomenon, and among the main reasons are the successes of modern medicine in the field of infertility treatment.

• In the early 80s, for every 80-90 births, there was one twins
• In the late 90s, for every 40-45 births, there was one twins
• In the early 1980s, there were one triplets for every 6,400 births.
• In the late 90s, there were one triplets for every 800-1300 births.

How often twins are born among representatives of different countries and peoples

In the US, there are 1 pair of non-identical twins for every 100 people in the population.
and for every 300 people - 1 pair of identical twins.

1/3 of all twins born in the US are identical. In Japan, the proportion of identical twins is 2/3 of all twins.

Hellin's Law

According to the pattern derived by American scientists, the frequency of the birth of twins before the widespread use of new methods of treating infertility was as follows:

More than one pair?

If you already have non-identical twins, the chances of getting a second pair are doubled. This is due to the fact that the body of a woman who once conceived dizygotic (non-identical) twins without the use of medications is able to produce several eggs during the period of ovulation.

If you are a twin (or have twins in previous generations)

Dear women! According to many studies, "twinhood" can be inherited (maternally).

• If you are a non-identical twin, you have about a 6 in 100 chance of having twins.
• If you are an identical twin, you have exactly as many chances as any other woman (from 1 to 2.5 chances out of 100, depending on the use of hormonal drugs).
• If your mother is a non-identical twin, your chances are above average.
• If your father is a non-identical twin, then the chances are average, just like if your husband is a twin, or has twins in the pedigree.
• If either of your parents is an identical twin, this will not affect your chances in any way.

More about trends

As the average age of women giving birth continues to increase (especially in developed countries), the likelihood of more twins being born is also increasing. In 1990, 39 women aged 45-49 in the United States became mothers of twins. In 1997, there were already 444. From 1980 to 1996, not a single woman aged 50-54 gave birth to twins. In 1997, 50 women of that age gave birth to twins and 13 to triplets.

But the main reason for the increase in the frequency of twin births continues to be the development of infertility treatments. Modern research shows that 80% of triplets were born as a result of the use of such methods.

The downside of increasing twin births is more underweight babies and preterm births, which in turn lead to higher infant mortality rates. In terms of statistics, the risk of premature birth and the birth of children of too small weight (before 1500) in the case of twins is 8 times higher, and with triplets 33 times higher than in the case of the birth of one child. In 1998, 41.7% of twins and 89.1% of triplets were born premature or very low birth weight.

Do you know that…

• The usual duration of pregnancy is 39-40 weeks, in the case of twins 36 weeks, with triplets 33-34 weeks, with quadruples 30 weeks, with quintuplets 28-29 weeks.
• 18-22% of twins are left-handed (in non-twins this percentage is 10).
• Identical twins have similar encephalograms.
• The science that studies twins is called gemellology.
• Often, twins talk to each other in a language that is not understandable to others. This phenomenon is called cryptophasia.

Which was published online on September 6, 2016. in the BMJ, to minimize the risk of perinatal mortality, delivery in uncomplicated dichorionic twin pregnancies should be discussed at 37 weeks' gestation. The authors of the meta-analysis also did not find convincing data that could justify the practice of delivery before 36 weeks in monochorionic twin pregnancies. This meta-analysis is the largest study to date of stillbirths and other neonatal outcomes in twin pregnancies and was the first to examine neonatal mortality by gestational age. These estimates of neonatal mortality at different gestational ages are important information for planning delivery in multiple pregnancies.

Twin pregnancies are known to be associated with a higher risk of stillbirth compared to singleton pregnancies, and this risk increases with increasing gestational age. A fairly common practice aimed at preventing stillbirth in uncomplicated multifetal pregnancies is early planned delivery, but preterm birth also leads to an increase in complications in newborns.

Currently, there is no generally accepted point of view on the optimal timing of delivery during pregnancy with twins. Various current recommendations mention 34 to 37 weeks of gestation for monochorionic twins, when the placenta is shared, and 37 to 39 weeks for dichorionic twins, when the placentas are different.

For this meta-analysis, the researchers conducted a systematic review of studies that had been published in any language up to December 2015. Then a meta-analysis was performed to assess the risk of stillbirth and complications in the neonatal period in monochorionic and dichorionic twins at different times, starting from 34 weeks of gestation, with an interval of 1 week. Included studies were also assessed for representativeness and risk of bias. Neonatal mortality was defined as death within 28 days of birth.

A total of 32 studies were included in the analysis, covering 35,171 twin pregnancies (29,685 dichorionic and 5486 monochorionic twins).

In dichorionic twins at 37 weeks' gestation, the risk of stillbirth with expectant management balanced the risk of neonatal death by delivery (pooled difference between risks, 1.2/1000 pregnancies; 95% CI −1.3 to 3.6; I 2 = 0%).

After 37 weeks, the risk of stillbirth significantly outweighed the risk of neonatal death due to delivery. Delaying delivery by as little as 1 week (up to a full 38 weeks) resulted in an additional 8.8 perinatal deaths per 1000 pregnancies (95% CI, 3.6 to 14.0 deaths per 1000 pregnancies; I 2 = 0%).

In monochorionic twins at 34 and 35 weeks, the risk of neonatal death was higher than the risk of stillbirth, but this result was not significant. At 36 weeks, there was a non-significant trend towards a higher risk of stillbirth compared to the risk of neonatal death (pooled difference between risks, 2.5; 95% CI −12.4 to 17.4/1000; I 2 = 0% ).

Rates of complications in the neonatal period, including the need for assisted ventilation, hospitalization in the neonatal intensive care unit, the frequency of respiratory distress syndrome and sepsis, steadily decreased with increasing gestational age in both mono- and dichorionic twins.

The authors of the analysis speculate that the policies adopted in many places for planned early delivery of multiple pregnancies may have led to a decrease in the number of full-term twins born, so that the risk of stillbirth at term may actually be even higher.

The information obtained on fetal and neonatal outcomes in twins of different gestational ages should be taken into account when planning the timing of delivery of individual patients, as well as when developing national and international measures to reduce the incidence of stillbirths and unexpected neonatal complications in infants born close to term.

Thus, this meta-analysis generally confirmed the information obtained in earlier studies and provided additional rationale for the current recommendations of the UK National Institute for Health and Clinical Excellence (NICE) for the management of twin pregnancies. Of course, the timing of delivery in multiple pregnancies should be chosen individually, but the available evidence base indicates that with uncomplicated dichorionic twins, delivery should be considered at 37 weeks, and with monochorionic twins, starting at 36 weeks.

Oddly enough, multiple pregnancy is not such a rare occurrence. If they were collected from all over the world in one place, then this number could be the population of two Frances! More than 100 million twins live on earth, and in Moscow alone there are at least 70 thousand couples. For every 100 newborns, there are one or two twin pairs. The record number of twins is born in Africa (in some tribes, every twentieth birth is multiple), the smallest is among representatives of the Mongoloid race.

Moreover, the number of multiple pregnancies is increasing. The statistical likelihood of getting twins or even triplets has been on the rise in recent years. Ten years ago, it was about 1:85, and now for every fifty births there is one twin or triplet. The number of quadruplets also increased: for example, in Germany from 1950 to 1983, quadruplets were born only 19 times, and in five years from 1983 to 1989 there were already 56 of them. A clear upward trend!

There are two reasons for the increase in the number of multiple births: women between 35 and 40 years of age are always more likely to give birth to twins than women younger than 35. Why this is so is not known, but it is an undeniable fact that there are now many more "late mothers" than another twelve years ago. However, the most important reason for the increase in multiple pregnancies is infertility treatment. If ovulation is stimulated by medications, then two or more eggs mature at the same time, and then fertilized at once. An increase in the number of triplets or quadruplets can be associated with hormonal treatment with absolute certainty.

In the occurrence of multiple pregnancy, the role of heredity is beyond doubt. So, in 31 out of 300 women in labor with a history of twins, relatives had indications of multiple pregnancies. Multiple pregnancy - the simultaneous development of two or more fetuses (twins). Its frequency ranges from 0.4 to 1.6%, but in recent years these figures have been increasing due to the use of drugs that stimulate ovulation (clomiphene, pergonal, etc.). The likelihood of multiple pregnancy increases with the age of the mother. Pregnancy with twins is observed most often and is 1:90, the frequency of three twins increases to 1:902, four - up to 1:903. Boys predominate among born twins.

The frequency of twin births may be related to the affiliation of the spouses to a particular ethnic group. So, in China it is 3:1000 live births, in Scotland - 12.3:1000, in Nigeria - 57.2:1000. These differences are associated with fluctuations in the frequency of the birth of fraternal twins, since the birth of identical twins around the world is kept at about the same level (3.5: 1000).

With the development of ultrasound methods and their application to determine the state of pregnancy, it has become apparent that the frequency of multiple pregnancy in humans can be higher than the numbers just given indicate. In fact, the rate of multiple pregnancy in developed countries is as high as 20:1000 pregnancies. In about 50% of cases, multiple pregnancy is not recognized, the reason for this is the high frequency of spontaneous abortions in the early stages in some women and spontaneous resorption of one of the amnions in others.

Many parents are involved today. And some of them dream of twins. Is it possible to plan the birth of twins?

Statistics

Over the past decade, the number of twins born has almost doubled. In European countries, including the Russian Federation, in the 1980s and 1990s, there were 1 twins for every 80-90 births. Today, every 40-50th birth ends with the birth of twins. However, these are not the highest figures. For example, in Nigerian women, every 22 births end with the birth of two children. But Chinese women can very rarely be content with the birth of twins, there are only one in 250 births.

How do you get twins

information Twins are born from a pregnancy resulting from the fertilization of two eggs that matured during one ovulatory cycle. They will have a different set of genes, and may be of different sexes.

The conditions under which 2 eggs can be obtained at once are as follows:

1. hereditary factor. Scientists confirm the fact that there are genes responsible for the development of multiple pregnancies. Therefore, if there are cases of the birth of twins in your family, then we can hope that you will be lucky to experience the happiness of double motherhood at the same time. Moreover, if this happened on the maternal side, then the probability is higher.
2. Multiple spontaneous ovulation. Usually, one egg cell matures in the ovaries of a woman every month, while there are two ovaries and they work alternately. Under the influence of various factors, the maturation of several eggs at once in one or both ovaries can occur.
3. late pregnancy. It is believed that in a woman over 35 years of age, the likelihood of multiple spontaneous ovulation is slightly higher, which means that the chance of becoming pregnant with twins also increases. This is due to the ongoing age-related changes in hormonal levels.
4. Contraception. It is noted that the chances of becoming pregnant with twins after the abolition of combined oral contraceptives (COCs) increases. This is due to the so-called “rebound effect”. The ovaries, after a long rest, begin to work so efficiently that they can produce several viable eggs.
5. Infertility treatment. More and more infertile couples are being helped by doctors to become parents. One way to increase the chances of pregnancy is stimulation. The drugs prescribed for this often lead to the simultaneous formation and maturation of more than one egg in the ovaries.
6. . During the in vitro fertilization procedure, two or more embryos are implanted into the uterus. Sometimes only one takes root, but often there are more.
7. Malformations of the uterus. Full or partial duplication of the uterus increases the chances of getting pregnant with twins.

The literature describes cases of so-called over-fertilization (the interval between the fertilization of two eggs in this case is more than one menstrual cycle, as a result of which there are two fetuses in the uterus with different gestation periods) and over-fertilization (when fertilization occurs during one ovulatory cycle, but as a result not one intercourse, but different ones).

So, some media confirmed this fact with stories that one woman gave birth to a baby, and a month later another one. There was also information about cases in which a woman gave birth to a black and white child from one pregnancy.

When can I find out about the conception of twins

For the first time, the fact of a multiple pregnancy can be established at the first visit to the gynecologist (the size of the uterus will be larger than the estimated gestational age). But with greater certainty, an ultrasound examination performed at the 5-6th week of pregnancy (detection of two embryos in the uterine cavity) helps to answer this question.

important Also, in the early stages of pregnancy, women bearing twins experience more pronounced toxicosis (nausea, vomiting).

Many couples try. Some want the child to grow up with a brother or sister of the same age. And others simply want to start a big family right away. Despite the fact that twins are born quite rarely, there are certain factors due to which you can significantly increase the likelihood of two babies being born at the same time.

What determines the birth of twins? Factors such as lifestyle, genetic predisposition, and even the ethnicity of partners come to the fore here. If a married couple is determined to have twins, the following information may be quite useful.

What are twins?

The birth of twins is determined by the type of fertilization of the mother's egg. The most common are dizygotic and In the first case, the embryos appear from two different eggs with simultaneous fertilization. Children conceived in this way usually have both external and sexual differences.

As for monozygotic twins, their conception occurs as a result of the splitting of one fertilized egg into two equal parts. The development of a monozygotic fetus is always characterized by the birth of children of the same sex with an identical set of genetic traits, one blood group and almost one hundred percent external similarity.

Reasons for the birth of twins

The main reason for the development of two embryos at once with a natural method of conception is the abundance of healthy, highly active spermatozoa in a man and the presence of an egg ready for fertilization. The effect is enhanced by unquestioning adherence to the recommendations of a specialist, maintaining a healthy lifestyle, as well as a predisposition to conceiving several babies in one or both partners.

Other reasons for the birth of twins are the consumption of foods or drugs whose constituent elements cause hyperovulation. However, doctors rarely recommend this kind of drugs in order to avoid the appearance of various complications during pregnancy, although they are quite effective.

genetic predisposition

An increased likelihood of the birth of several babies at the same time is present in families in which such cases were recorded on the maternal side. So, if a woman's mother or grandmother gave birth to twins, she has an increased chance of giving birth to twins too.

However, it is not so simple. Of great importance in this case is the combination of it in both partners. More often, heredity in terms of the birth of twins manifests itself after one generation. But even with the combination of the above circumstances, the chance for a successful outcome of the conception of twins is no more than fifty percent.

With weak heredity or insufficient strength of sex hormones of partners, the probability of having twins or twins varies from five to fifteen percent.

Factors contributing to the birth of two or more babies at once

As statistics show, the chances of having twins or twins in a healthy woman without a genetic predisposition are only about three percent. In general, there are a number of factors, the presence of which increases the likelihood of having two or more babies at the same time.

The chance of having twins increases if:

• in the family on the maternal side there have already been cases of the birth of twins or twins;
• the woman has African roots (Europeans are in second place in terms of the likelihood of having twins, followed by Asians and Hispanics);
• the woman has already had successful pregnancies (this trend is associated with an increase in the capabilities of the human body);
• a woman is tall, leads a healthy lifestyle, eats well, or has some excess weight.

Nutrition and vitamins

In families in which partners lead an unhealthy lifestyle, eat poorly and neglect the intake of food rich in vitamins and useful trace elements, the likelihood of having twins is significantly reduced.

At the conception of a child and directly during its bearing, any vitamin complexes are useful. However, as practice shows, the birth of twins becomes more likely with the active intake of high-folic acid supplements, which are now available in almost any pharmacy.

Good, wholesome nutrition, rich in fresh, environmentally friendly products, not only leads to the birth of a healthy child, but also increases the chance of having twins. Significantly less such chances in people who are underweight.

If we talk about complete, good nutrition, then it should provide a uniform weight gain without causing harm to health and one's own well-being. Naturally, trying to increase the likelihood of having twins by any means, it is better to consult in advance in a reputable clinic. After all, only the application of the knowledge of a trained, experienced and practicing doctor makes it possible to hope for a positive result.

What is the probability of having twins if you resort to the help of a specialist?

Going to an experienced specialist can increase the chance of conceiving twins. In modern medical practice, there are enough professional doctors who can help give birth to twins to almost any couple.

Currently, the issues of conception of twins are most often solved by using the method of in vitro fertilization. Conceiving children in this way can cost a young couple a lot. However, the introduction of several healthy sperm at the same time into the mother's egg by artificial means significantly increases the likelihood of achieving the desired goal.

Finally

What determines the birth of twins? This issue is still not fully understood and remains shrouded in mystery. However, it is certainly known that an increased likelihood of conceiving two or more babies is transmitted through the generation.

It is worth noting that there are a sufficient number of families in which there are cases of conception of several twins, twins and even triplets. There are also families where twins or twins are grandparents, cousins, nephews and nieces. Therefore, the answer to this question is best known to nature. All the best!