Prevention of Rh conflict during pregnancy.

Causes of incompatibility between mother and fetus blood

All people on the planet are divided into two groups based on blood type: Rh-positive and Rh-negative. When planning a baby, spouses must undergo appropriate testing. It is important to determine what kind of blood the future parents have. If the Rh factors do not match, some difficulties will arise during pregnancy. The blood of the mother and the unborn child is often incompatible by Rhesus, by group, and also by other criteria. In this case, hemolytic disease of the newborn occurs. During the disease, hematopoiesis is inhibited or red blood cells are destroyed due to antibodies produced in the mother's blood. With a 95% probability, fetal pathology will be caused by Rh incompatibility. Only in 5% of cases the disease is explained by incompatibility in other erythrocyte systems.

In the Rh system, it is customary to distinguish 6 different antigens: D, d, C, c, E, e. They can be combined in different ways in a person’s blood, and the course of pregnancy depends on this. Doctors attach the greatest importance to the main antigen - D. It is found on the surface of red blood cells in 85% of men and women. This antigen indicates a positive blood type. It is typical for European residents. If the antigen is missing, then the person's blood is considered Rh negative.

In genetics, it is customary to indicate Rh status with the letter D. Information about it is contained in two forms of the same gene, which are called alleles. To put it simply, Rh factor is indicated by two letters D at the same time. A positive Rh factor can be Dd or DD. Negative blood is indicated as dd. The child receives one letter each from his mother and father. For this reason, people have different combinations of antigens.

How is the Rh factor inherited?

• DD woman + DD man = everyone will have a DD Rh factor as their heir. Mom, dad and children will be positive.
• DD woman and Dd man (or vice versa) = all children will have Rh factor DD or Dd. The probability of each option is 50%. In this situation, the partners are Rh positive, but one of them has a gene associated with Rh negative. Children will exclusively have positive blood.
• Female Dd and male Dd = children have a 75% chance of having a positive Rh factor. In 25% of cases it will be negative, that is, dd. In this case, both parents are positive, but they have a gene associated with Rh negative. For this reason, there is a possibility of giving birth to a child whose blood will be different from that of mom and dad.
• dd female and dd male = all heirs will have the same blood as their parents. In this case, both mom and dad are Rh negative.
• DD female and dd male (or vice versa) = all children will be born with the Rh factor Dd.
• Dd female and dd male (or vice versa) = half of the children will have a positive Rh factor, and the rest will have a negative Rh factor.

In the above two situations, one of the parents has negative blood, and the other has positive blood. Difficulties during pregnancy appear only in a situation where an Rh-negative woman is carrying a positive child. Pregnancy requires increased monitoring by medical professionals. When a woman is Rh negative and a man is positive, then doctors immediately believe that the fetus will be positive. If you focus on genetics, then there is a chance of having an Rh-negative child. At the same time, medical specialists decide to play it safe, so they carefully monitor the woman’s pregnancy.

Prevention of Rhesus conflict

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 (the father has a positive Rh factor), the woman’s blood is tested repeatedly during pregnancy for the presence of Rh antibodies. If they are not there, it means that the woman is not sensitized and there will be no Rh conflict during this pregnancy. Immediately after birth, the baby's Rh factor is determined. If it is positive, then no later than 72 hours after birth the mother is given anti-Rhesus immunoglobulin, which will prevent the development of Rh conflict in a subsequent pregnancy. You would be wise to take anti-D immunoglobulin with you when going to the maternity hospital (of course, if you have a negative Rh factor).

Rh-negative women should carry out the same immunoglobulin prophylaxis within 72 hours after:

• ectopic pregnancy
• abortion
• miscarriage
• transfusion of Rh positive blood
• platelet transfusions
• placental abruption
• injuries in a pregnant woman
• amniocentesis, chorionic villus biopsy (manipulation of membranes)

What difficulties might you encounter?

Rh conflict is possible in a situation where a woman with negative blood is carrying a positive child. In this case, there is a high probability of hemolytic disease of the fetus. This pathology progresses in stages.

First, the person is immunized. The expectant mother acquires immunity, which must fight foreign bodies. The placenta is considered an effective barrier, but there is still a risk of the baby's red blood cells entering the woman's circulatory system. The body immediately reacts by producing IgM antibodies. They are not able to cross the placenta, and therefore do not lead to the development of hemolytic disease. At the same time, antibodies increase the sensitivity of the expectant mother’s immunity. They are intensively produced during repeated penetration of red blood cells. IgG antibodies appear in the blood, which quickly cross the placenta and lead to the breakdown of the baby’s red blood cells.

For the process of sensitization to develop, it will be enough that 0.05 ml of the fetus enters the woman’s bloodstream. With each subsequent pregnancy, the risk of immunization increases significantly. After each birth of a baby, it increases by 10%. For this reason, it is important to preserve the first pregnancy and carry out preventive measures.

The likelihood of sensitization increases in the following situations:

• Pregnancy outside the uterine cavity.
• Spontaneous or induced abortion after 8 weeks.
• Detachment of placental tissue after the birth of a child, threat of termination of pregnancy.
• Negative changes in the placenta of the chronic type.
• Premature placental abruption in the last weeks of gestation.
• Difficult childbirth, which ends in operations and injuries.

The second stage of hemolytic disease is the penetration of antibodies from an adult through the placenta into the child’s bloodstream. For most mothers, this percentage is observed no earlier than 18-20 weeks. It occurs due to placental insufficiency. The risks increase as the time of delivery approaches. Antibodies can enter the fetal bloodstream during delivery. In this situation, the child will develop fully throughout pregnancy. The disease will appear only after birth.

Rarely, antibodies do not cross the placenta, and immunized women give birth to a healthy baby. Expectant mothers should not count on a positive outcome, since if the outcome is unfavorable, they will have to take care of prevention.

At the third stage, antibodies begin to act on the fetus. Having penetrated the child’s bloodstream, they attach to the surface of red blood cells, provoking destruction. In this regard, a significant percentage of bilirubin is released, which colors the mucous membrane and dermis in a yellow tint. Bilirubin can enter the brain and cause encephalopathy. Generalized fetal edema may also develop. Pathology can lead to DIC syndrome, and it often causes the death of the fetus inside the womb.

What's happening?

When fetal red blood cells carrying proteins of the Rh system enter the blood of a mother with Rh negative, they are perceived by her immune system as foreign. The body begins to produce antibodies to destroy the baby's red blood cells. This causes large amounts of a substance called bilirubin to appear in his blood, which can damage his brain. As the fetus's red blood cells are continuously destroyed, its liver and spleen try to speed up the production of new red blood cells, thereby increasing in size. In the end, they also cannot cope with replenishing the loss of red blood cells. Severe oxygen starvation sets in, and a new round of serious violations develops. In the most severe cases, this can lead to fetal death.

Features of pregnancy management for women with negative Rh factor

An obstetrician-gynecologist is obliged first of all to determine the Rh and blood type of a man and a woman. After the tests, the doctor assesses the likelihood of red blood cell breakdown in the unborn child. He clarifies whether there was an ectopic pregnancy before, whether the woman had abortions, or underwent a blood transfusion. A healthcare professional must determine whether sensitization is present. It is necessary to perform desensitization, and, if indicated, take preventive measures to prevent pregnancy complications.

The obstetrician-gynecologist will assign the expectant mother to one of the observation groups. A woman may be classified as a primigravida with no sensitization. The expectant mother can be assigned to the group of sensitized patients without symptoms of hemolytic disease. The third group includes women with hemolytic disease.

The management of pregnancy directly depends on which category the woman belongs to. Medical specialists consider each case individually and select the most appropriate tactics for a particular situation. Timely prevention allows women to give birth to a healthy baby and avoid complications during pregnancy. If you do not see a medical professional, your risk of developing hemolytic disease will increase.

Prevention

Recommendations for preventing the development of blood group conflict:

• try to avoid abortions, as this increases the likelihood of complications during subsequent pregnancies;
• observe preventive measures against infection with infectious diseases (flu, hepatitis), which weaken the body of the expectant mother;
• undergo routine examinations during pregnancy in a timely manner;
• Be careful when carrying a baby so as not to provoke placental abruption.

Modern medicine has many means to prevent the development of blood group conflict. The specialists of the Mother and Child clinics will do everything possible to maintain the health of the expectant mother and baby.

What is the danger?

The conflict poses a danger primarily to the fetus. It can cause a serious condition known as hemolytic disease. The development of anemia, as well as hypoxia and acidosis, is possible. Damage to some organs may occur. As a rule, we are talking about the heart, brain, kidneys, spleen, central nervous system, liver.

If there is no prevention and timely measures are not taken, there is a possibility of complications: death of the fetus in the womb, stillbirth, miscarriage, birth of a child with severe health problems.

In expectant mothers themselves, the conflict often does not manifest itself in any way, although symptoms similar to those of gestosis are possible.

Causes of woman sensitization

Maternal blood can come into contact with fetal red blood cells in the following cases:

• when a woman is transfused with Rh(-) Rh positive blood;
• during platelet transfusion;
• during an abortion;
• in case of miscarriage;
• during ectopic pregnancy during attachment of a fertilized egg to the fallopian tube;
• for injuries during pregnancy;
• in case of placental abruption;
• with bleeding during pregnancy;
• with a biopsy of chorionic villi in order to diagnose certain fetal pathologies in the early stages of pregnancy.

There is a risk of conflict in the events listed above if there is contact between the blood of mother and child and the woman is sensitized. The probability of this is higher, the more red cells of the fetus enter the woman’s bloodstream. If, upon contact of maternal blood with the baby’s red blood cells, the pregnant woman begins to produce antibodies to the Rh antigen, then the process is considered irreversible. That is, during the second pregnancy you cannot do without special treatment.

If antibodies are detected?

If a pregnant woman has antibodies in her blood and their titer increases, then we can say that an Rh conflict has begun. Modern medicine allows Rh-negative women to give birth to more than one child, even if antibodies are detected. The latest equipment makes it possible to monitor the condition of the fetus and detect the development of hemolytic disease. Today there are conditions for intrauterine blood transfusion through the umbilical cord to the fetus under the control of ultrasound equipment. Thus, it is possible to maintain the child in a normal condition until birth.

What if there are no antibodies?

If there are no antibodies in the blood, most likely, the first pregnancy will pass without complications, the child will be healthy. To prevent sensitization, the expectant mother is administered immunoglobulin at the 28th week, and then again immediately after birth (within the first three days) if the child was born Rh-positive. In addition, a course of treatment is carried out if events have occurred that could have caused contact between the blood of the mother and the fetus, but the release of antibodies did not occur.

To prevent Rh conflict, a course of treatment with immunoglobulin is prescribed