What is blood incompatibility?
If the expectant mother's blood is Rh(-) and the expectant father's blood is Rh(+), (or vice versa) Rh incompatibility comes into play. This does not always cause a problem in the baby. If the baby has an Rh(+) blood group, the expectant mother's defense mechanism perceives the unborn baby's blood cells as a foreign substance and moves to break them down. If the expectant mother's defense mechanism has encountered these cells for the first time (such as during a first pregnancy), then the baby will be saved until the defense system develops its "weapons".
However, these Rh(+) cells in the mother's body may not give the baby a chance with a more effective defense in the secondpregnancy , since they will have learned. If the necessary precautions are not taken in time, in one of the next pregnancies, when this defense system of the expectant mother encounters the Rh(+) cells in the blood of the unborn baby, this time it will spend only time to "get the weapons out of the stockpile" and will go into a violent defense, and the baby's life will be in danger.
How is the baby harmed in blood incompatibility?
Every substance that is not a human tissue and every organ added to the body through transplantation is treated as a foreign substance. These foreign substances are called antigens (those that do not match the body's genetic structure). These antigens try to activate the body's defense system in which they are placed.
Antigens can be substances such as bacteria, viruses, protozoa, and transplanted organs such as kidney, liver, or heart, in addition to blood group building blocks.
The defense system takes action to explode the foreign substance and produces antibodies (substances called "objects" produced against foreign substances) that can recognize that substance. There is a key-lock relationship between the antibody and the antigen. In this way, it works to bind to the antigen where it sees it, break it down and remove it from the system.
Antibodies that have emerged against the Rh(+) blood group of the baby in an Rh(-) expectant mother are revealed as a result of an Indirect Coombs (IDC) test in the mother's blood. The result of this test should be negative under normal conditions. If it is positive, there may be an immunized Rh incompatibility. The severity of the positivity is directly related to the damage the disease has caused to the baby.
Following birth, the Direct Coombs (DC) test is performed on the baby's blood to measure the antibodies produced against the baby's Rh(+) antigens from the mother's blood. The result of this test should also be negative under normal conditions.
Preventing Rh incompatibility by immunization
In babies of partners with Rh incompatibility, the formation of immunized Rh incompatibility can be prevented. In order to achieve this, it is absolutely necessary to prevent the first encounter of the Rh (+) blood group of the baby of the mother with Rh (-) blood group. For this reason, Anti-Rh immunoglobulins (antibodies) are used, which are available on the market under many names (example: RHOGAM). These drugs are referred to as “incompatibility shots” in the community.
These drugs contain antibodies against the Rh (+) blood group. These antibodies are the same as those produced by Rh (-) mothers who have previously encountered Rh (+) blood. When these antibodies are injected into the mother through the hip, they pass into the mother's blood and find all the Rh (+) antigen-carrying cells, and the mother's immune system destroys these Rh (+) antigens before they can see them, preventing the first contact.
The real danger begins in the second pregnancy
This incompatibility does not occur in all pregnancies with Rh incompatibility. The reason for this is that allergic reactions do not occur when the baby is first exposed to an allergen, so it is not expected to occur in a first pregnancy.
However, if the allergen is present in large amounts during the first encounter, an allergic reaction may occur. During pregnancy, serious bleeding that may cause excessive blood flow between the mother and the baby may occur, and Rh incompatibility may occur during the first pregnancy. For this reason, Rh incompatibility generally becomes a problem when the second pregnancy occurs.
What precautions should be taken before birth?
It is mandatory to know the blood type of the mother-to-be before giving birth. If the mother-to-be has a document that may not state her blood type correctly, a test must be performed to determine her blood type again.
Knowing your blood type is very important in order to take precautions against possible blood incompatibility. One example of this is that if the mother is Rh (-) and the father is Rh (+), the baby that will be born will be 50% or 100% Rh (+) according to Mendel's Laws, depending on the father's genetic structure (heterozygous or homozygous). Since scientific research has not determined how the genes that determine the father's blood type are arranged, it is generally assumed that in every case where the mother is Rh (-) and the father is Rh (+), there is a classical "blood incompatibility" or "Rh incompatibility".
Since the most important treatment for blood incompatibility is prevention, the rules stated below must be followed.
• The blood types of the spouses should be determined in the early stages of pregnancy. • If there is Rh incompatibility in the prospective mother and father, the indirect Coombs test should be repeated at appropriate intervals. • If necessary, an early protection injection (Rh hyper immune globulin) can be administered in the 28th week of the first pregnancy. • If the baby's blood type is Rh positive; an Rh hyper immune globulin injection that will prevent antibody production should be administered within 72 hours in order to protect subsequent babies. • The mother's sensitization puts the baby at risk. For this reason, the antibody levels in the blood are checked in the later stages of pregnancy. If the antibody level is high, the baby's health status should definitely be monitored in a perinatology clinic with special tests and appropriate treatment should be administered. • In miscarriages older than 3 months, immunoglobulin should be administered at full dose. Since red blood cells start to form in the fetus after 6-8 weeks in the first 3 months, it is appropriate to administer low-dose hyperimmunoglobulin (protective injection). • In abortions performed for medical reasons or upon request, Rh hyperimmunoglobulin should be administered before the intervention, and if possible, the operation should be performed with a vacuum.
Even if there is an abortion or miscarriage, necessary precautions should be taken
Now you know that Rh incompatibility does not affect the mother's health. However, this situation can cause very serious problems in the baby. In general, the fact that expectant mothers do not experience any problems in their first pregnancy is seen as a good advantage in terms of taking precautions.
In line with the information given, a couple with Rh incompatibility;
In case of miscarriage or abortion,
After ectopic pregnancy surgery, the protective vaccine (known as the incompatibility shot in the community) that prevents the formation of antibodies in the mother must definitely be administered within the first 4 days.
Since the baby's blood type is unknown during pregnancy, if the baby's blood type is determined to be Rh (+) in the 28th week of pregnancy, the protective vaccine should be administered within the first 4 days after birth.
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