If a pretty girl walks by, you may hear many an admirer say: “That’s my blood type all over!”. Well, the probability that one has at least something in common with the beautiful stranger, namely the blood group, is not so small at first glance. There are only four blood groups, and the beauty must belong to one of them. Why should it not be coincidentally the same, although the blood group equality or inequality does not include unconditional sympathy or antipathy in itself.
Blood Groups
About 15% of all people lack this Rh factor in their blood. They are Rh-negative. One can readily transfuse the blood of Rh-positive people to such Rh-negative people. However, in the body of the Rh-negative person, defense substances are subsequently formed against the Rh-positive blood. The blood groups A, B, AB and 0 have been known to us for a long time, and every person knows that they have to be determined in advance, e.g. for blood transfusions, because not every blood is “compatible” with everyone. On the contrary, serious complications can occur when unsuitable blood is transfused. Everyone also knows that, for example, in paternity suits, the court physicians determine the blood group affiliation secondarily, in addition to a DNA test, and in favorable cases can exclude with certainty a disputed paternity with their determination alone. These “favorable” cases are when the father belongs to a different blood group than the mother and the child in turn belongs to a different one. Unfortunately, these clear cases are quite rare, a finding that is easily explained by the small number of only four different blood groups, which, moreover, are not evenly distributed among mankind. In all the many cases, however, in which mother, child and supposed father belong to the same blood group, paternity cannot be attributed to the latter without further ado.
Rh factor Rh factor
Scientific research thus set out to find further distinguishing characteristics and discovered, among other things, the blood subgroups or blood factors m and n. However, they play an increasingly rare role in forensic medicine. Today, scientific research into blood group characteristics has become an almost independent branch of medicine. During animal experiments with the blood of rhesus monkeys, the Americans Landsteiner and Wiener discovered another blood factor in the last century which, as was later shown, is also present in human blood. Since it was first found in experiments with rhesus monkeys, it was called the Rh factor. It was recognized that it was responsible for some types of incidents in transfusions of blood of the same group. About 15% of all humans lack this Rh factor in their blood. They are Rh-negative. It is possible to transfuse the blood of Rh-positive people to such Rh-negative people without any complications during blood transfusion. In the body of the Rh-negative person, however, defense substances (antibodies) are subsequently formed against the Rh-positive blood. When Rh-positive blood is transfused again, these antibodies come into play and cause damage to the transfused blood and the patient’s own blood, thus leading to a potentially fatal transfusion incident. Such antibodies are also formed in the body of an Rh-negative mother who has given birth to an Rh-positive child. Such a mother must receive only Rh-negative blood if a blood transfusion becomes necessary at a later date; otherwise, there is serious danger to her life.
Rh factor and pregnancy
If a second or repeated pregnancy occurs in an Rh-negative mother who has a completely healthy child by her Rh-positive husband (the antibodies were formed only during the first pregnancy or during childbirth), and a miscarriage is also considered to be a pregnancy in the same way, this time the antibodies formed will be directed against the health of the child-to-be, who will be born either prematurely, often dead, or with serious health disorders that may render him or her unable to live. The same can happen if the Rh-negative mother has already had a blood transfusion once before the first pregnancy, with the donor blood containing the Rh factor. Under these circumstances, already in the first child born from an Rh-positive man, the antibodies formed in the maternal blood become effective and are directed against the life of the child-to-be.
Rhesus factor prevention and treatment
Medicine, of course, has not stopped at the discovery of the Rh factor and its effects, but has successfully endeavored to avert all impending dangers. If it is a matter of blood transfusion, this is relatively simple. Every doctor has the duty to determine not only the blood group but also the Rh factor before blood transfusion. In this way, the dangers of transferring unsuitable blood are avoided. However, it is difficult to prevent an Rh-negative woman who already carries the antibodies to Rh-positive blood (for example, due to previous blood transfusion with Rh-positive blood or due to a previous pregnancy with Rh-positive child) from the threat of premature birth or birth of a non-viable child. In the pregnancy consultation, a blood sample is taken from each woman in the 4th month, which is also tested for the presence of the Rh factor, among other things. In case of the absence of this factor, in case of repeated pregnancies or previous blood transfusion, blood control examinations take place at regular intervals, which provide the doctor with information about the presence or strength of the Rh-positive blood defenses (the defenses are strongest at the end of pregnancy). The baby’s life can be saved by immediate blood exchange, replacing all of the little baby’s blood with blood from a suitable donor. Here, every minute is precious. It goes without saying that deliveries of Rh-negative women should take place in a hospital. Fortunately, not all Rh-negative mothers experience the complications described above. This is due to the fact that not all Rh-negative people form equally strong antibodies against Rh-positive blood. Only in a small fraction of cases do the dangers described here occur. However, knowledge of these things has made us understand many a blow of fate that used to affect our families. Today, thanks to preventive health measures in Germany, we can avoid such complications, at least if the expectant mother has visited the pregnancy consultation at her gynecologist in time and the necessary measures are taken there.
