Infertility and cases of pregnancy during testosterone cycles . ""

I have a friend who is going through this, he used steroids for 5 years in a row and stopped using them .. After a year without using steroids he went into the endocrinium and the doctor said he is infertile, which he can no longer conceive a woman .. A doubt I have: --- The HPTA is off during the cycle, not after it. That's the real reason to use HCG at 500 IU per week intra-cycle, that's what I know !!! My biggest question is, how do some guys get their women pregnant during the use of exogenous testosterone, and by the theory that I read and hear your HPTA would be turned off ?? Note: I'm talking about cases that guys do not use HCG in the cycle to generate LH in the testicles .. How is it possible for guys to grind their wives in cycles, with the HPTA turned off ???