There is some concern with TRT impacting fertility. Basically, it isn’t a sure enough thing to rely on as birth control. As a little anecdotal evidence, I was watching the documentary Generation Iron with the current Mr Olympia contestants and some of them had young children. And we know they’re on more than 200 mg of test. But if having kids was a major concern of mine, I would be hesitant to commit to TRT unless I really needed it. I just had my first kid and don’t want anymore so it can only help me. You can, like you said, always come off and use hCG to get things going again. Alternatively, you could try hCG mono therapy. I didn’t feel any benefit from it but Chris from Good Looking Loser said he loves the way hCG makes him feel. Everyone’s different.