Question about when on HRT

I know on HRT some doctors will give HCG in order to keep their patients fertile. However, from what I have read, HCG only signals the release of LH and not FSH. So when someone takes it for HRT to keep child making intact, they’re left out in the cold when it comes to FSH production? Am I wrong?

human Menopausal Gonadotropin (hMG), human FSH (hFSH), recombinant human FSH (rhFSH), and occasionally Gonadotropin releasing hormone (GnRH) are used to maintain spermatogenesis when hCG alone doesn’t seem to do the trick.