Q: I am a 32 years old female. I gave birth to a baby boy six years back. He required a blood transfusion because his haemoglobin was very low. I was told that it was due to a bad CW antibody. Now I am planning for another child but this child will have a different father. I have haemochromatosis and require 500 ml of blood after every four months and I am not sure if this will affect my pregnancy. Will my second child also suffer from low haemoglobin at birth?

A:Human blood group systems are mainly of two types: 1. ABO and Rh. The Rhesus system is more complicated as there are a variety of alphabetically named markers, each one of which may be either present or absent. Within the Rh group system it is mainly the anti Rh, (D) antigen antibody that is usually screened. However, there are many other less common antibodies that are either not screened at all or are screened only under special circumstances. Some of the irregular blood group antibodies that are seen include antibodies against the antigens such as Cw, Kp-a, Js-a and others. Coming to Cw antigen antibody, the Rh antigen C" originally described by Callender & Race in 1946, is a rare blood group antigen that may sensitize a Cw negative mother. Your case is an example of this rarely reported unusual blood group antigen incompatibility, leading to severe haemolytic disease in the newborn. What you need to remember is that you are now a sensitised mother and therefore, you will be having a high titre of anti Cw antibodies in your blood. That can be detrimental to your next baby if it happens to be Cw positive. This in turn depends upon your partner/spouse because if he happens to be Cw positive, there is a very high chance of your child from him being Cw positive as well, which then can be problematic. So, what I would suggest is to get the screening of your spouse done and take it from there.