Are orcs immortal??

[Tuor Turambar,Cursed by the Valar]

Elves don't reproduce in conditions of war or captivity. In Morgoth's Ring, when Elven marriage customs are being discussed, it is said that Elves do not have children during times of war, unsettlement, captivity, or hardship

Yes, that is helpful to know. Unfortunately, I have not read morgoths ring, so I was not aware of this. Even so, i do not find it impossible that morgoth has found a way to force the orcs to reproduce. They are corrupted, so, to me, it does not seem odd that elvish traits, such as those mentioned in the quote, do not appy, for lack of a better term.