What is the problem when b positive blood group women marry a o men?

The problem that arises when a B-positive blood group woman marries an O-positive blood group man is the potential Rh incompatibility. Rh incompatibility occurs when the mother is Rh-positive and the father is Rh-negative. In this case, the fetus can inherit the Rh-negative blood type from the father, while the mother's immune system recognizes the fetus as foreign and produces antibodies against the Rh-positive blood cells. These antibodies can cross the placenta and attack the fetal red blood cells, leading to a condition called erythroblastosis fetalis.

Erythroblastosis fetalis can cause severe anemia, jaundice, brain damage, and even death in the fetus or newborn. The risk of erythroblastosis fetalis increases with each subsequent pregnancy, as the mother's immune response to the Rh-positive blood cells becomes stronger.

To prevent erythroblastosis fetalis, Rh-negative women who are pregnant with an Rh-positive fetus can receive a medication called RhoGAM (Rh immune globulin). RhoGAM is an antibody that binds to and destroys any Rh-positive red blood cells that may have entered the mother's circulation, preventing the development of antibodies against Rh-positive blood.