His and Her Health

Hello everyone. My husband has low testostarone and he has been taking hormone gel since September of last year. The gel seems to increase his sex drive and it has brought his testostarone count up from where it had dropped. The doctors do not know why he is not producing the hormone on his own. We are not currently trying to have children, but I'm wondering if we will have trouble conceiving if his body does not produce adquate hormone on it's own? Or will the testostarone gel be enough to boost his sperm count? He has never had a sperm count done and I told him to wait until we are ready to have children, but we both wonder if his condition will cause us problems. Any help would be much appreciated. Thanks!