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Sometimes at the appointment of patients who plan to become pregnant, the doctor emphasizes the fact that they have Rh-negative blood, so there may be some complications during pregnancy.
Let’s consider what the blood group and the Rh factor are and whether Rh-negative blood is really associated with health risks for the expectant mother or baby.
On the surface of erythrocytes (red blood cells) there are specific proteins (antigens) based on the presence or absence of which the blood is divided into groups. The most significant classifications: according to the ABO system (known as blood group) and the Rhesus factor (Rh).
The main blood groups according to the ABO system:
- Blood group 0 (I): no antigens (universal red blood cell donor)
- Blood group A (II): A antigens are present
- Blood group B (III): B antigens are present
- Blood group AB (IV): A and B antigens are present
Rhesus factor (Rh) is the second clinically significant classification of blood after the ABO system. It was named after the monkey Rhesus, in which this factor was first discovered.
The key antigen is antigen D. If it is present on the surface of the erythrocyte, then the blood is considered Rh-positive (Rh+), if not, then, accordingly, Rh-negative (Rh-).
The majority of people on the planet, about 85%, are Rh(+) positive, the rest will be Rh(-) negative.
Determination of blood group and Rh factor is extremely important during blood transfusion and during pregnancy. In the case of blood transfusion, the incompatibility of these two systems can pose a serious threat to health and life.
Group antigens of the ABO system are determined in the erythrocytes of the embryo from about the 5-6th week of pregnancy, and the Rhesus factor (Rh) – from the 8th. The incompatibility of the mother and the embryo by blood group or Rh can lead to the production of specific antibodies and the occurrence of an immune reaction (sensitization), the most frequent manifestation of which is hemolytic disease of the fetus and newborn.
ABO incompatibility is more often observed with 0(I) blood group in the mother and A(II) – in the father (and the fetus) due to the fact that the A antigen has the strongest antigenic properties. Hemolytic disease with ABO incompatibility is extremely rarely severe and if it occurs, it has manifestations of mild anemia or jaundice in the baby.
A negative blood group during pregnancy does not always pose a threat to the baby.
For example, there may be different combinations:
- Rh(-) parents will have an Rh(-) child, the blood of the fetus and the mother are similar, there will be no conflict
- if an Rh(-) mother and an Rh(+) father have an Rh(-) child, the pregnancy proceeds smoothly
- if the mother’s blood group is Rh(+), and the child is Rh(-), there will be no protein incompatibility.
Problems arise when an Rh(-) mother gives birth to an Rh(+) child. The blood in the woman’s body can begin to produce antibodies to destroy foreign proteins of the child.
But, if an Rh(-) woman is pregnant for the first time and there has been no transfusion of incompatible blood or termination of pregnancy for more than 8 weeks, there is no need to worry. The blood in the mother’s body has not yet come into contact with foreign erythrocytes and has not learned to “fight” with them.
What is important for Rh(-) women to know during pregnancy:
- it is desirable to determine the blood group and Rh factor of one’s own and the husband’s at the stage of pregnancy planning (sometimes the father’s blood test can also rule out Rh-positive blood in the child)
- at around 12 weeks pregnant, your baby’s blood type and Rh factor can be determined using a blood test – a non-invasive RhD NIPT prenatal test taken from you (if your baby is Rh(-), he is not at risk of Rh disease and he is not will require additional monitoring or treatment)
- іf an Rh(-) woman has a risk of Rh-conflict during pregnancy, blood for determination of antibody content must be given every month until the 28th-32nd week of pregnancy
- if the antibody screening is negative, your obstetrician-gynecologist will give you Rhesus immunoglobulin at around 28 weeks of pregnancy and then again within 72 hours after delivery (if the fetus is Rh-positive) to prevent the formation of antibodies in subsequent pregnancies;- if the screening for antibodies is positive, special attention is paid to ultrasound examination of the fetus and observation of the titer of antibodies in the mother’s blood (after the 32nd week of pregnancy – 2 times a month, and from the 35th – once a week).
Thus, Rh-negative blood does not threaten the health of the expectant mother in any way, does not carry the risks of the course of the first pregnancy with any Rh of the child, but the pregnancy of an Rh (+) baby requires careful observation in Rh(-) women with a difficult obstetric history or in particular history of blood transfusion.