In addition to the blood types A, B, AB and O, the red blood cells are also responsible for another characteristic of blood, the Rhesus factor. The Rhesus factor can lead to Rhesus disease, and is important for pregnant women.
Rhesus factor for pregnant women
About 84% of people has the Rhesus factor and is Rhesus(D) positive. The other 16% lack the Rhesus factor, and are called Rhesus(D) negative. If a Rhesus(D) negative woman is expecting a Rhesus(D) positive child, this Rhesus(D) positive factor in the child can lead to antibody formation in the mother. During the pregnancy, but mainly during the delivery, the Rhesus D positive red blood cells of the child can enter into the blood system of the mother. Because the mother's body considers these Rhesus(D) positive red blood cells to be foreign, it creates Rhesus(D) antibodies. This usually only occurs after the delivery. That is why the risk of problems with the first child is small.
Antibodies for the child
During pregnancy, the mother transmits antibodies to her unborn child via the placenta. This gives the child an initial immune response against all kinds of diseases, via the mother. If the mother has created Rhesus(D) antibodies during a previous pregnancy, they remain present in her blood and can end up in the circulation of the (unborn) child via the placenta during a subsequent pregnancy. This can cause problems if she is pregnant with a Rhesus(D) positive child. These maternal antibodies break down the child's red blood cells and cause anaemia.
This may make the (unborn) child ill, sometimes so seriously ill that a blood transfusion in the mother's womb is necessary. After the birth, the baby may become ill from the breakdown products that are in the blood. The baby will then be yellow in colour. We call this Rhesus disease. It is important to remove these waste products from the blood. This can be done by treating the child with a UV light (a kind of sun bed). In serious cases the baby's blood must largely be replaced through a so-called exchange transfusion.
Fortunately, Rhesus disease can be prevented. To ensure this, Rhesus(D) negative women are give a Rhesus injection during the 30th week of pregnancy and after birth, if the child proves to be Rhesus(D) positive.
The Rhesus injection is made from human plasma. The plasma is collected from voluntary, unpaid Dutch donors. The Rhesus injection contains antibodies that clean up the Rhesus(D) positive red blood cells of the child that may have entered the mother's circulation. This prevents the mother's body from having the time to recognize her child's red blood cells as foreign. That is why she does not make any antibodies, preventing Rhesus disease. Thanks to the current methods for preventing and treating Rhesus disease, it is only very rarely fatal for the child any more.
Few plasma donors
There are too few plasma donors with the required high levels of Rhesus(D) antibodies in their blood. Therefore, the blood bank is always looking for donors who do have enough Rhesus(D) antibodies in their blood. Do you already donate blood and do you have high levels of Rhesus(D) antibodies?