What is anti-pernicious anaemia factor? Explain in detail.

Anti-pernicious anaemia factor is vitamin B12. Vitamin B12 is required by the body for producing normal healthy red blood cells. In pernicious anaemia, due to the lack of vitamin B12 in the body, red blood cells do not divide normally and are larger in size. Due to large size, they can not come out of bone marrow leading to low RBCs in blood.
As, vitamin B12 is anti-pernicious anaemia factor, proper amount of it in the body do not allow the disease to occur. When body get proper amount of vitamin B12, normal RBCs are produced in the body and thus prevent anaemia.