Haemolytic disease and the rheasus blood group

[Cheman]

Haemolytic disease and the rheasus blood group...

Why do you get haemolytic disease in a baby ( not first baby) if the mother is Rh- and her anti D antibodies cross the placenta, yet it is fine to tranfuse Rh- blood to a Rh+ recipient, which will also contain anti D antibodies?

Thanks in advance.

 

[Cheman]

I've just noticed there is a slight flaw in my question 4get it. Sorry.

 

[ravenprp]

Haemolytic disease, also known as hemolytic disease of the newborn (HDN), is a condition in which a mother's Rh-negative blood type is incompatible with her baby's Rh-positive blood type. This can lead to the mother's immune system producing antibodies against the baby's blood cells, causing them to break down and leading to anemia, jaundice, and potentially serious complications.

The reason why this occurs in a baby and not in a transfusion scenario is because the immune response is different in each case. In the case of a transfusion, the Rh-negative recipient's body is already aware of their own Rh status and has developed antibodies to protect against Rh-positive blood. When Rh-negative blood is transfused, the recipient's body recognizes the foreign Rh-positive blood and mounts a quick and effective immune response to destroy it.

However, in the case of a pregnancy, the mother's body is not aware of the Rh status of her baby and does not produce antibodies until after the first pregnancy. During the first pregnancy, there is usually no issue as the mother's body has time to develop antibodies and the baby is usually born before the antibodies can cause harm. But in subsequent pregnancies, the mother's body has already developed antibodies and these can cross the placenta and attack the baby's blood cells, causing haemolytic disease.

This is why it is important for Rh-negative mothers to receive a special injection of Rh immunoglobulin during and after their first pregnancy. This injection prevents the mother's body from developing antibodies against the Rh-positive baby's blood cells.

In summary, the difference between a transfusion scenario and a pregnancy scenario is that in a transfusion, the recipient's body is already aware of their own Rh status and has developed antibodies, while in a pregnancy, the mother's body is not aware of the baby's Rh status until after the first pregnancy. This highlights the importance of proper medical care and interventions, such as the Rh immunoglobulin injection, to prevent haemolytic disease in subsequent pregnancies.