Just curious... For how many years can a female reproduce?

Is a non-spayed female fertile for all her years, even as a senior, or do they go through a "menopause" like humans? Of course, a cat that goes through litter after litter probably won't get to be that old anyway, but I'm just curious how nature works that way in cats.

As far as I know they can reproduce indefinitely, although their litter size may get smaller. I know of several geriatric dogs that have given birth to over 10 puppies!