Define Erythroblastosis Fetalis
Besides the risk of a mismatch reaction during a second or during any subsequent blood transfusion, giving Rh-positive, blood involves risk in case of young Rh-negative girls.
This is because of the possibility of complication during pregnancy if the girl happens to have a Rh-positive foetus in her uterus any time later in life. The chances of any abnormalities resulting from Rh incompatibility are negligible during first pregnancy, 3% during second and 10% during third. This is due to following reasons:
1) Red cells of the foetus are unable to cross normal placenta. There has to be some abnormality in the placenta before foetal red cells can enter the maternal circulation.
2) Foetal red cells may be destroyed by maternal plasma before they can induce an antibody response. E.g., if mother is 0, Rh negative and the foetus is A, Rh positive, the foetal red cells would be haemolysed by the anti-A antibodies present in the maternal plasma.
3) If the foetus and mother happen to be of same group, i.e., A,B or AB but mother is Rh -ve and foetus Rh +ve, during 2nd and subsequent pregnancies, mother gets sensitize with Rh antigents of fetal blood, resulting in production of anti-Rh antibodies, which will destroy foetal RBC, causing 'erythoblastosis foetalis'.
Although erythroblastosis foetalis may be treated by exchange transfusion, the prevention is routinely attempted by desensitizing the mother for production of Rh antibodies during pregnancy. The desensitized mothers don't respond to foetal Rh+ve RBCs. Thus erythroblastosis foetalis is prevented.
Apart from the Rh incompatibility as a complication leading to loss of blood, there is another condition wherein the RBCs are deficient. This is referred to as anaemia, a disorder related to deficiency of erythrocytes. As a student of dietetics, you must be familiar with anaemia and its consequences.