One of the first and most important tests that a pregnant woman should have is the blood test. This basic test determines what type of blood you have and what your Rh factor is. And it is that the Rh factor will play an important role in the health of the baby .
Rh factor is a protein present in cells and, depending on their blood type, each person has specific proteins of that blood type on the surface of red blood cells. There are four blood groups: A, B, AB, and O.
In turn, each of the four blood groups is classified according to the presence or not on the surface of the red blood cells of another protein that determines the Rh factor. If the person is a carrier of this protein, they are Rh positive; if she is not a carrier, she is Rh negative.
Most of the population, 85%, has that certain sequence of amino acids that in common language is usually called Rh +. There are many possible combinations depending on the Rhs of the parents, but Rh sensitization or Rh incompatibility can only occur when the mother is Rh factor negative and the father is Rh positive .
Rh negative mother and Rh positive father
Of all the possible combinations, the risk exists when the blood group of the Rh- woman and the Rh + man are combined, although there would be no risk if the baby inherits Rh- from the mother .
But when an Rh negative woman and an Rh positive man conceive a child, there is a possibility that the baby has health problems. It is possible that the baby that is forming within the mother who is Rh negative has Rh positive blood that she inherited from the father.
About half of the children with an Rh negative mother and an Rh positive father are Rh positive.
There is no risk of Rh incompatibility in the first pregnancy
The mother is not normally sensitized in the first pregnancy, but in the second or subsequent ones; For these purposes, any previous pregnancy is considered a first pregnancy, even if it has not reached term.
This means that Rh incompatibility is generally not a problem when it comes to a first pregnancy since, unless there is some type of abnormality, the blood of the fetus does not enter the mother’s circulatory system during pregnancy. .
However, during labor, the mother’s blood and the baby’s blood can intermingle. If this happens, the mother’s body recognizes the Rh protein as a foreign substance and begins to produce antibodies (protein molecules in the immune system that recognize, and then destroy, the foreign substances) to attack the Rh proteins that enter her. blood.
A pregnant Rh-negative woman can also come into contact with Rh protein (something that could produce antibodies) in Rh-positive blood transfusions, miscarriages, and ectopic pregnancies.
During subsequent pregnancies, red blood cells from the fetus can pass into the mother’s bloodstream as she feeds it through the placenta.
Rh antibodies are not harmless in subsequent pregnancies , since if the mother conceives an Rh + baby, the woman’s body will now recognize Rh proteins as foreign bodies. Then your antibodies will go into the baby’s bloodstream to attack those cells.
What is the Coombs Test?
That is why it is so important to detect from the beginning of pregnancy if the mother has begun to generate antibodies. To do this, a test called the indirect Coombs test is performed, also known as the indirect antiglobulin test.
It is a non-invasive test that is performed through a blood sample from the mother in the first trimester, in the 8th or 9th week, and is repeated in the second trimester, in the 26th week of pregnancy.
Consequences of Rh incompatibility for the fetus
If the mother’s body begins this “attack” it can lead to dilation and breakdown of the baby’s red blood cells. When this condition occurs, it is known as hemolytic disease or Rh disease of the newborn .
This disease, whose scientific name is “erythroblastosis fetalis”, is a blood disorder in which, given the different blood types, a mother produces antibodies during pregnancy that attack the red blood cells of her own fetus.
The name erythroblastosis is due to the appearance in the circulating blood of a high number of erythroblasts, which are precursors of red blood cells, which have been released into the circulation.
The severity of this condition can vary widely. In some cases, the baby has no symptoms of the disease; in other cases it can lead to the death of the baby before or shortly after birth. This disorder can be treated in utero (before the baby is born) through an intrauterine transfusion.
When the baby is born, signs that can present as signs of Rh incompatibility are: enlarged liver or spleen, generalized swelling, jaundice, and anemia. After birth, depending on the severity of the condition, a blood transfusion is usually necessary.
What is the treatment for RH incompatibility?
In the past it was much more complex, but today the treatment is very simple. To prevent sensitivity caused by Rh incompatibility, special immunoglobulins called RhoGAM are used .
Whether the test results are positive or negative, if the father is Rh positive and the mother negative, the pregnant woman receives an injection of anti-D gamma globulin around week 28 to prevent the production of antibodies during delivery, when the The mother’s blood can be mixed with the baby’s, and another injection within 72 hours after delivery to prevent the mother from making antibodies.
If the woman has already developed the antibodies, the pregnancy should be followed closely to control that the Rh levels are not too high. Only in exceptional cases, if the incompatibility is very serious and could put the baby at risk, are blood transfusions called exchange transfusions performed during pregnancy and after delivery.
Exchange transfusions replace the baby’s blood with Rh-negative red blood cells to minimize the damage that can be caused by the circulation of Rh antibodies already present in his bloodstream.
Photos | iStockphoto and Arek Socha on Pixabay
