I am not Positive.
But I think that Renesmee CAN have children. Since she is neither Vampire or Human, she changes. The reason Vampire females can't have children is because they do not, but since Renesmee does change I am pretty sure she can.
I think her and Jacobs children would be, a mix of all three I suppose. They would be wolf descendants, or "shape shifters" and would possibly either have very strong skin when they are in human form as the vampire, or possibly pale. I also think that having such a creature, of mixing vampires, warewolves, and humans together that Renesmee's children might not want to hurt vampires, and the warewolf vs. vampire battle, might come to actually peace.
But since Renesmee is part human that must mean that she could have children, since her mother was humaan when she conceived Renesmee that means that since Renesmee is part human she can still have children. And if this confuses you let me put it simpler, since Remeesmee is part human from when her mother birthed her that means that she could still probaly still have children. But i am not sure