Most people have no idea what an Rh factor is. In normal life, its presence or absence does not entail any painful consequences. However, in the case of pregnancy, an inappropriate combination of rhesus factors of parents can lead to a so-called Rh-conflict. So, what should one know about Rh factor and pregnancy while planning to conceive?
Rhesus factor is an antigen (protein). It is located on the surface of red blood cells – erythrocytes. It can be present (Rh positive), or absent (Rh negative). According to medical statistics, about 85% of people are Rh-positive. The remaining 15% are Rh-negative.
Rhesus-conflict occurs either with the transfusion of Rh-incompatible blood, or with the pregnancy of a woman with Rh negative, if the blood of the fetus is Rh-positive.
Rh Factor and Pregnancy
At the beginning of pregnancy, you will have to take a blood test for the blood group and its Rh status – the presence of the Rhesus (Rh factor) – the protein that is present on the surface of red blood cells. If you have an Rh factor, you are Rh positive, like 85% of the rest of the people on the planet. If you do not have Rh factor, then you are Rh-negative. You will need to take certain precautions during pregnancy. What is the significance of the Rh factor and pregnancy?
If you are Rh negative, then there is a high probability that your blood will be incompatible with the blood of your child, who is likely to be Rh-positive. In most cases, Rh-incompatibility does not harm the mother or her child, provided that this is the first pregnancy. But if your child’s blood gets into yours, then your immune system will start producing antibodies against Rh-positive blood. If this happens, you will become rhesus-sensitized. Thus, if you get pregnant a second time and the fetus is Rh-positive, these antibodies can “attack” the blood of your child.
Rh Sensitization: How to Avoid?
Fortunately, you can avoid Rh-sensitization if you are given injections of a drug called Rh-immunoglobulin whenever there is a chance that your blood is mixed with the blood of your baby.
If you are Rh-negative, this is your second pregnancy and you did not receive Rh-immunoglobulin injections before, a blood test will show if you have antibodies that attack Rh-positive blood. Note that such antibodies are produced not only after the birth of the child, but even after miscarriage, abortion, ectopic pregnancy and even after stillbirth.
If you already have antibodies, then it’s too late to do immunoglobulin injections. Unfortunately, if your child turns out to be Rh-positive, then he is likely to have some problems. If you do not already have antibodies, Rh-immunoglobulin will help prevent them from appearing.
Rh Conflict: How Does it Work?
When the erythrocytes of the fetus, carrying the proteins of the Rh system, enter the mother’s blood with negative rhesus, they are perceived by her immune system as alien ones. The body begins to produce antibodies to kill the baby’s red blood cells. In this case, a large amount of a substance called bilirubin appears in the baby’s blood. This can damage the brain of the fetus. Since the fetal erythrocytes are continuously being destroyed, the liver and the spleen try to speed up the production of new red blood cells, while increasing in size. In the end, they cannot cope with the replacement of red blood cell loss. As a result, there is a strong oxygen starvation. Other serious violations may develop as well. In the most severe cases, this can lead to the death of the fetus.
How Does the Blood of the Mother and the Child Mix?
Usually during pregnancy the blood of the child does not mix with the blood of the mother. Although a small number of blood cells penetrates through the placenta. But a significant mixing of blood almost never occurs until the delivery begins. This is why Rhesus incompatibility is usually not a problem if your child is the firstborn. If the blood does not mix before delivery, the baby will be born earlier than your immune system will start producing enough antibodies to cause problems.
However, you will need to get an injection of Rh-immunoglobulin immediately after birth, if your newborn baby is Rh-positive. Thus, immunoglobulin will prevent the creation of antibodies that can attack the blood of an Rh-positive baby during a future pregnancy. Without treatment, the probability of antibodies production is more than 15%. After the injection this figure reduces to almost zero.
About 2% of women with a negative Rh factor develop antibodies to their baby’s Rh-positive blood during the third trimester. That’s why such women receive the first Rh-immunoglobulin injection at the 28th week of pregnancy. This injection allows preventing the production of antibodies until delivery.
If there is a chance that the baby’s blood is mixed with yours at any other time, then you need to immediately get immunoglobulin. The acceptable term for the injection is the next 72 hours. This usually occurs during invasive procedures. For example, amniocentesis or choriocentesis (chorionic villus biopsy), or in the following cases:
- after miscarriage or abortion;
- after ectopic or molar pregnancy;
- if the child was born dead (stillbirth);
- with abdominal injuries during pregnancy;
- if the future mother has vaginal bleeding.
Rh-conflict and Pregnancy: What’s the Danger?
The presence of Rh factor is inherited. The threat of Rh-conflict exists only if the future mother is Rh-negative (Rh-), and the father is Rh-positive (Rh +). In this scenario, in 75% of cases, the mother and child will be Rh-incompatible.
But if a woman has an Rh negative factor and a man has an Rh positive factor, this is not a reason to refuse to create a family.
The first pregnancy of such a pair is likely to be normal. If a woman has not previously met with Rh-positive blood, then she does not have antibodies. Therefore, the risk of Rh-conflict with the fetus is also absent. During the first pregnancy the organism produces not so much antibodies. If the number of fetal erythrocytes permeating the mother’s blood was significant, there remain “memory cells”. In subsequent pregnancies these cells organize the rapid production of antibodies against the Rh factor.
With Rh-incompatible pregnancy, much depends on how it ended. After miscarriage, Rhesus sensitization (development of antibodies) occurs in 3-4% of cases, after medical abortion – in 5-6%, after ectopic pregnancy – approximately in 1% of cases, and after normal birth – in 10-15%. The risk of sensitization increases after caesarean section or if there was a placental abruption. That is, everything depends on how many red blood cells of the fetus got into the bloodstream of the mother.
Rh Factor and Pregnancy: The Consequences of Rhesus-Conflict?
Rhesus-negative women should take care about their body and listen to its signals.
Such an attitude will help to prevent:
- edema of the fetus;
- disturbance of the brain, problems with speech or hearing of the child.
To protect the baby from these consequences, women with negative rhesus during pregnancy must timely take all the tests that are prescribed by the doctor.
In the maternity welfare center doctors always check the pregnant woman’s Rh factor. If it is negative, it is necessary to determine the rhesus of the father. At the risk of Rh-conflict (the father has a positive Rh factor), the woman’s blood is repeatedly examined for the presence of antibodies to the fetal erythrocytes and their number. Until the 32nd week of pregnancy, this analysis is carried out once a month, from 32nd to 35th – twice a month, and then until the birth weekly.
By the level of antibodies in the blood of the future mother, the doctor can determine the possible onset of Rh-conflict and draw conclusions about the presumed Rhesus factor in the child.
In addition, immediately after birth, doctors determine the baby’s Rh factor. If it is positive, the woman must get immunoglobulin injection no more than 72 hours after the birth. This will prevent the development of Rh-conflict during the next pregnancy.
The same is performed within 72 hours after ectopic pregnancy, abortion, miscarriage, Rh-positive blood transfusion, platelet transfusion, placental abruption, trauma in pregnant women, as well as amniocentesis and chorionic biopsy.
Rh Factor and Pregnancy: Treatment
If a pregnant woman has antibodies and their number increases, this indicates the onset of a rhesus-conflict. In this case, treatment is needed in a specialized perinatal center, where both the woman and the child will be under constant supervision.