Why is bone marrow transplantation associated with a high risk of infertility?

Yeah, bone marrow transplant is associated with a high risk of infertility and the reason for this is that before the transplant itself, patients undergo high-dose chemotherapy. And usually the agents they use are alkylating agents which are associated with a high-risk of infertility and also some of them may need to have total body irradiation as well and so combination of these treatments would put them at high-risk for infertility. In fact, there is a sort of recent paper showing that very few bone marrow transplant survivors are fertile or have had children.