[Grishnakh]

That's really not necessary. "Immortal" people aren't going to live forever; something is eventually going to kill them, like a speeding bus, or a skydiving accident, etc.

Also, it's been proven over and over that when people have more education and resources, they breed a lot less, which is why all the developed nations are looking at zero or negative population growth if you ignore immigration. Make people biologically immortal and they'll end up not having many kids at all, on average.

I think you're worried about something that isn't going to be a problem.