Determination of blood group by parents. About the inheritance of blood group. What blood type will the child have? Can children be born if parents have different blood types?

Hello, Larisa!

Human blood is divided into groups according to the presence or absence of special substances in it - antigens A and B (each gene can carry one antigen or none). This system for dividing blood groups is called the AB0 system.

1st blood group 0(I) -00 - no antigens
2nd blood group A (II) - A0, AA - antigen A is present
3rd blood group B(III) - B0,BB - antigen B is present
4th blood group AB (IV) - AB - both antigens are present.

The blood type of a child, according to Mendel's law of inheritance, is determined by two genes, one gene the child receives from the mother, the second from the father.

The options and percentage probability of inheriting a blood type are taken from a basic combinatorial calculation.

If parents have the first and third blood groups, their child can only have the first or third blood group, since there is no antigen A in the blood of the child’s parents, and accordingly there is nowhere for it to come from in the blood of the child himself:

I(00) + III(B0) = I(00) — 50%
I(00) + III(B0) = III(B0) - 50%

I(00) + III(BB) = III(B0) - 100%

In fact, exceptions to the rules are quite rare, and children are diagnosed with a blood group whose antigens are not in the blood of their parents, that is, which, according to Mendel’s law, cannot exist.

This is explained by the fact that human blood may contain antigen A or antigen B, which are specifically suppressed and are not detected by standard blood tests. In this case, the blood behaves like blood of another group. For example, a parent with the first blood group may have a hidden antigen A, which can be transmitted to the child and manifested in him. In this case, parents with the first and third blood groups may well have a child with a second or fourth blood group, because the parents’ blood actually is not such.

Taking into account this phenomenon (“Bombay phenomenon”), your couple’s child may have a second blood group, although this is unlikely.

Inheritance of the Rh factor in human blood occurs regardless of the inheritance of blood type.

The Rh factor is a special protein that is present in the red blood cells of 85% of people (such blood is considered Rh positive). In its absence, they speak of Rh-negative blood. The blood factor is denoted by the Latin letters Rh with a plus or minus sign, respectively. To study Rhesus, as a rule, one pair of genes is considered.

A positive Rh factor is designated DD or Dd and is a dominant trait, while a negative Rh factor is dd, a recessive trait. In the union of people with heterozygous presence of Rh (Dd), their children will have positive Rh in 75% of cases and negative in the remaining 25%.

The inheritance of the Rh factor by a child is determined according to the table:

Thus, it is most likely that the child of your couple will have blood of the first or third positive group.

Since ancient times, blood has been considered a special, almost magical liquid. It was with her that children and adults were related. That’s what they said – “blood relationship”, emphasizing the special strength of this connection. Today, people are trying to explain character traits or eating habits through blood group. It is therefore not surprising that parents are interested in what kind of blood their child may have.

And it is equally important for doctors to know what blood type the parents of the unborn baby have. And this question is by no means an idle one. The course of pregnancy and the health of mother and child, and the likelihood of possible complications, depend on how they are combined in the parents and the unborn child. Some of these relationships have already become a medical axiom, while others are only talked about by practicing doctors.

Let's try to figure out how the blood groups of children and parents are related: the inheritance table will help us with this.

Although this scarlet liquid was always treated as something special and its connection with human life and health was understood, the real properties were not known for a long time. Only in 1900, the Austrian physician and scientist Karl Landsteiner, who studied blood serum, made a discovery that later brought him the Nobel Prize, and allowed humanity to use the transfusion of this life-giving liquid in treatment as a completely ordinary and familiar procedure.

The scientist took blood from himself and five of his employees, separated the red blood cells from the serum and mixed their samples with the serum of different people. Karl Landsteiner discovered that red blood cells behave differently in different combinations. In some cases, the red blood cells "stick together" to form clots, but in others they do not.

Decoding the results allowed him to initially identify three blood groups depending on the presence or absence of special particles, which he designated as A and B, and the absence as 0. Later, his successors identified another group, which contained both AB markers at once. Then they began to be designated by Roman numerals. Today, the generally accepted classification of blood groups looks like this.

This made it possible to determine blood compatibility and predict its behavior when transfused from one donor to another.

Rh factor

Further research into the properties of blood revealed another factor that affects its compatibility. In 85% of people, a special lipoprotein was found located on the membranes of red blood cells, called the Rh factor. Those who have it are Rh positive (Rh+), those who do not have it are Rh negative (Rh-).

The presence or absence of this antigen does not affect human health in any way, but is of great importance for the expectant mother. Since the child, forming and growing in it, has its own blood type with the Rh factor, this can lead to a conflict with the maternal immune system, especially with a second pregnancy.

That is why parents of the unborn child are asked to undergo tests to determine the blood type and Rh factor. If the Rh factor of the father and mother is the same (both positive or both negative), then there is no reason to worry. But if the rhesus levels of the expectant parents are different, then the onset and course of pregnancy requires closer attention from doctors.

The option is especially difficult when the mother is Rh negative and the father is positive, since most often the baby inherits Rh positive. This leads to the occurrence of Rh conflict between the mother’s body and the fetus, especially with repeated pregnancies.

Why the blood types of the child and parents do not match

How to recognize a group in children

To find out the possible blood type and Rh in children, you need to know exactly the characteristics of this vital moisture of the father and mother. The inheritance of these parameters is determined by the same laws of genetics as the inheritance of hair or eye color.

Table 1. Inheritance of a child’s blood type depending on the blood groups of the father and mother

Table 2. Inheritance of the blood type of the Rh system, possible in a child, depending on the blood types of his parents

As we know, a baby can only get what his parents have. But sometimes parents may hide hidden recessive genes behind a dominant trait, and then two brunettes suddenly give birth to a blond child. But two blondes cannot give birth to a brunette. So it is with the Rh factor.

A positive Rh factor is a dominant trait, so it is most often inherited. If both parents have negative Rh, then their children will have a similar Rh- without variants. But in mixed couples, or even if both parents are Rh positive, but there are hidden Rh- genes, in this case there is a possibility of having a baby with Rh-.

Pattern of inheritance

As already noted, the blood type is determined by the presence or absence of agglutinogens A and B in its composition. The type of blood a baby will have is influenced by the groups of parents. The easiest way is if both parents have the first group. This means that there is neither A nor B in the blood, therefore their children can only have the same group. In all other cases, various options are possible for children. It will be possible to know exactly about the baby’s blood type only after the analysis has been performed.

Human blood groups. Tips for parents

A child’s blood type is not just an interesting statistical indicator, but also a factor that can have a significant impact on the condition of the newborn and the characteristics of its development. Parents should determine in advance the degree of probability of what blood type the baby may have and what the likelihood of developing an Rh conflict is. This will allow you to prepare for the possibility of activation of abnormal conditions that require immediate response and medical intervention.

Some experts even encourage future parents to carry out a similar calculation before deciding to start a family, in order to exclude the possibility of children being born with mutational or genetic diseases.

Factors that determine a child's blood type

All people are traditionally divided into four categories depending on their blood groups. To determine it, you just need to find out what the indicator of agglutinogens (A and B) and agglutinins is in human red blood cells and plasma:

• First (0) . There are no agglutinogens, only agglutinins are present.
• Second (A0). Agglutinogens A and agglutinins are present, with the former in the leading position.
• Third (B0). Agglutinogens B and agglutinins are present, the former again being in the leading position.
• Fourth (AB). A very rare combination in which agglutinogens A and B are present together.

The listed indicators in children directly depend on the data of the parents. Despite the fact that there is a detailed table that allows you to determine what kind of blood the baby will have, you can only find out exactly about all the probabilities of events by conducting thorough laboratory tests.

How is the Rh factor inherited?

The development of Rh conflict can pose a serious danger to the fetus, so at the moment experts pay attention immediately after establishing the fact of pregnancy. It develops in Rh-negative women and Rh-positive men, but not necessarily in 100% of cases. Modern medicine has made it possible to develop a number of measures aimed at suppressing the pathological condition, but this is a complex and protracted process.

It happens that parents with positive rhesus have a negative child. The Rh factor can differ in physiological indicators, and there is nothing unusual in this. Everything is explained by the specific structure of blood cells, the peculiarities of the presence of protein on the surface of red blood cells and its activity. Rhesus inheritance is not always passed directly from parents to children, it all depends on which genes predominate in them, dominant or recessive.

We determine the child’s blood type according to the parents’ data

If you know what blood the mother has and what the father has, you can try to independently determine what indicator the baby will have. A child's blood type is inherited by passing on one gene from each parent:

• Parents with the first group can only have a similar baby.
• If one of the parents has the first group, and the other has the second, then the child will receive either first or second blood.
• If one of the parents has the first group, and someone has the third, inheritance occurs in exactly the same way. The result will be either first or third blood.
• When combining the indicators of the first and fourth groups, either the second or the third group can be obtained.
• The fourth group in combination with the second or third will give any result except the first group.
• Parents with the second and third blood groups can give birth to any babies, and it is impossible to know what kind of blood will be in which case. True, there are several tests that can predict the possible outcome as accurately as possible.

Advice: Do not panic and immediately think that the child was replaced in the maternity hospital if the calculation carried out independently does not give the desired result. It happens that antigens A and B are present in the human body in a passive form and do not manifest themselves in any way. True, this happens mainly in children from Asian countries.

This is only basic data, the final result may change under the influence of certain factors. It is impossible to influence these processes; you can only get as close to the result as accurately as possible using numerous tables and a calculator. In isolated cases, even the established rules do not apply, so the baby’s blood parameters must be determined immediately after his birth, even if both parents have the first indicator.

Incompatibility of mother and child according to blood parameters

Finding out in advance what the mother’s blood data is and what the baby is expected to have is necessary for one more reason. Not many people understand that there is a risk of developing conflict not only in the Rhesus, but also in the group. When there are various antigens in the blood of the fetus and mother, a woman may begin to produce antibodies directed at the child.

Most often this happens in the following cases:

1. The first or third in the mother, the second in the fetus.
2. The first or second in the mother, the third in the fetus.
3. Any indicators in the mother, the fourth in the fetus.
4. Different blood counts in parents are also a mandatory indicator for establishing the presence of group antibodies in the pregnant woman and the fetus. The only exceptions are those cases when the father has the first blood group.

Despite the apparent complexity of the processes, all indicators can be established in just a few studies. At the same time, you should not rely only on your own knowledge; it is better to double-check everything by trusting professionals. If you know what blood type the child may have, it will be possible, if necessary, to make timely adjustments to the coordination of the pregnancy, think through a plan for the birth and further management of the baby. We must not forget about the risks of bleeding during childbirth; doctors must be prepared for anything in order to reduce the possibility of a negative outcome of a natural and so important process.

From time immemorial and until the beginning of the 20th century, practically nothing was known about the birth of a child and his heredity. The situation changed at the turn of the century, when the Austrian scientist Karl Leinsteiner, studying red blood cells, determined that the composition of blood in people differs and depends on genetic processes.

This discovery became a new milestone in medicine, explaining why, during a transfusion, the donor's working material did not help the patient.

Nowadays, thanks to the research of great scientists, it is possible to learn a lot about a child long before his birth. To avoid hereditary or mutational diseases, it is recommended to take a blood test for the compatibility of future parents even before going to the registry office. Having the necessary information, you will know how to act in the future and will be able to provide your baby with a fulfilling future.

For example, Rh conflict can occur during conception in an Rh-negative woman and an Rh-positive man.

What determines a child's blood type?

ABOUT- the absence of agglutinogens in a person indicates that his blood belongs to the first group.

A- in an active position belongs to the second group.

IN- can only be in the active position with the third group.

A and B– erythrocyte antigens in joint action indicate a rare case of a person having a fourth blood group.

Depending on the combination of parental antigens and their Rh factor, the child’s blood type is determined. Accurate data can only be obtained in laboratory conditions.

Inheritance of the Rh factor?

When a child with a negative Rh factor is born in a family of parents with a positive Rh factor, great surprise arises, and even sometimes mistrust in the form of reproaches and doubts about the honesty of the spouse. But there is a simple explanation for this problem.

Rh factor is an antigen (protein) located on the surface of erythrocytes, red blood cells. About 85% of people have this same Rh factor, that is, they are Rh positive. The remaining 15% who do not have it are Rh negative. These factors are denoted by the letters Rh, positive with a plus sign, negative with a minus sign. To study Rh, usually take one pair of genes.

DD or Dd is a positive Rh factor, and is a dominant trait, dd is negative, recessive.
If a couple has heterozygous Rhesus (Dd), then in 75% of cases their children will also have positive Rhesus, and 25% negative.

If parents have Dd x Dd factors, then their children will have DD, Dd, dd. Heterozygosity appears in a child as a result of the conflict of the mother’s Rh-negative factor, so to speak, and can be transmitted to many generations.

How to determine a child's blood type based on his parents?

(table No. 1)

- Parents with blood type I (the most common) will produce offspring without red blood cell antigens (O).

If the husband has group 1, the wife has group 2 and vice versa, then the children will have similar positions. I(O) and III(B) are combined in the same way.

The fourth group in one of the parents can lead to any indicators except the 1st group. And the partner will not be able to influence this in any way.

The combination of groups II(A) and III(B) gives unpredictable results. The baby can be born with any of 4 types of groups.

An exception is the phenotype with A and B antigens in a passive form. They simply do not manifest themselves in any way, they are extremely rare and only in Asian countries, due to which the case is called the “Bombay phenomenon”.

(table No. 2)

(table No. 3)

Incompatibility of mother and child by blood type

But there may also be incompatibility in blood groups. If the blood of the mother and the fetus contain different antigens, the mother's blood can produce antibodies in relation to the child's. Incompatibility is possible with group I or III in the mother and group II in the fetus; Group I or II in the mother and group III in the fetus; any blood group in the mother, when the fetus has group IV. If the mother and father have different blood groups, then the presence of group antibodies in the pregnant woman and the fetus must be checked. The exception is a combination in which the father has the first blood group.

Attention!

But it happens that there is no time to find out or determine the blood type of one of the transfusion participants, then it is possible to infuse a minimum portion of blood of the first group with negative Rhesus - this is universal blood, compatible with all types of antigens.

By the way, the first group together with the second are the most common in the world. And the rarest of all is the fourth group, whose carriers are only 3-5% of all people.

Currently, about 30 blood group systems are known, but one of the most significant is the ABO system, according to which four blood groups are distinguished. The second most important is the Rhesus system - blood is divided into 2 groups. You can read more about these systems in the article “Blood type and Rh factor”.

What blood type will the child have?

The blood type of the unborn child is strictly dependent on the blood groups of the parents. According to the same principles of inheritance, a child receives his own blood type, eye color, skin color, and hair color. The genetic inheritance of blood type is strictly natural. But this does not mean that if both parents, for example, have the second blood group, then their children will only have the second.

It turned out that if parents have the second (II) and third (III) blood group, then their children can equally inherit any blood group. And vice versa, if mom and dad have the first (I) and fourth (IV), then the children will inherit a blood group different from their parents - second (II) or third (III). Also, the first group (I) is excluded if one of the parents has the fourth blood group AB (IV).

Blood type AB (IV) is quite rare in all parts of the world, regardless of nationality and race. It cannot be inherited, but is formed in the fetus under the influence of genes received from the parents - A and B.

Blood groups. Table

In addition to the simple interest “What blood type will the unborn child have?” There is another good reason to know what blood type your baby might have. During pregnancy, not only Rh conflict can occur, but in some cases, blood group conflict as well.

If the mother has the first blood group (I), and the child has any other, she can produce antibodies against it. In this case, it is necessary to check the presence of group antibodies in women with the first blood group, since if they are present, the development of hemolytic disease of the newborn by blood group is possible. However, a severe form of hemolytic disease of the newborn is rare, occurring only in isolated cases.

The blood of a certain number of people may contain a protein called the Rh factor (Rh). According to the Rh factor, all people can be divided into Rh-positive Rh(+) and Rh-negative Rh(-). Inheritance of the Rh factor occurs independently of the inheritance of blood type.

If a pregnant woman has Rh(-), and her husband has Rh(+), then in half the cases the planned child will have a positive Rh factor (Rh+). Rh conflict occurs during pregnancy of a woman with Rh negative, if the blood of the fetus is Rh positive.

It is possible to say exactly which Rh factor the child will inherit only in one case: if both parents have negative Rh status. All children of such a couple will have an Rh negative factor. In all other cases, the Rh factor can be anything.

When red blood cells from a Rh-positive fetus enter the blood of a Rh-negative mother, they are perceived by her immune system as foreign. The body begins to produce antibodies to destroy the baby's red blood cells. Since the fetus's red blood cells are continuously destroyed, its liver and spleen try to speed up the production of new ones, thereby increasing in size. As a result, they cannot cope, severe oxygen starvation occurs, which causes even more pathologies. In the most severe cases, this can lead to fetal death.

At the antenatal clinic, a pregnant woman must be checked for the Rh factor. If it is negative, it is necessary to determine the father's Rh status. If there is a risk of Rh conflict (if the father has Rh(+)), the woman’s blood is repeatedly tested for the presence of antibodies to fetal red blood cells and their number.

During the first pregnancy, the immune system of the expectant mother only “gets acquainted with strangers” (Rh+ red blood cells), few antibodies are produced and a conflict may not arise. However, “memory cells” remain in the woman’s body, which, during subsequent pregnancies, quickly “organize” the rapid and powerful production of antibodies against the Rh factor. Consequently, the risk of fetal damage increases with each subsequent pregnancy.