So my whole theory is that Renesmee will be able to have kids. In the book Bella describes that the reason that she and Edward could have kids was b/c her body chagnes month to month whereas a female vampire doesn't change. Vampire men are pretty much the same as human men b/c men don't change month to month anyways and can have kids basically until they die. so we know that Renesmee has a heart beat so that attributes to her human qualities and she also grows...but she can also only survive on blood but she eats as well, but vampires don't have any sort of bodily functions but they never mentioned her having to bathe or go to the bathroom like humans do. Her skin is strong like humans and she has more strength than a normal human and Carlisle and them know how to care for the baby so they could safely deliver it. But okay let's say Nessie grows and goes thorough puberty like human girls, the problem is she's full grown in only 7 years so will her "change" stop once she's full grown, or will she even go through it to begin with? Or will she just be able to have kids and not have to go through the monthly thing? I mean they say that the point of imprinting is so that they can further the species and breed bigger better werewolves. So she has to be able to have kids or else why would he imprint? Slash...this brings me to Leah that's a little off topic but with Leah I don't think she's a dead end I think that once she imprints her whole not have a cycle will continue b/c think about it...having one isn't conducive to being a werewolf and all, once she imprints it will return so that she can have kids. If anything i think that she's a sign of a mutation for the better like w/ Jacob and Sam. they're so huge and bigger than everyone else but usu. that happens when genes diversify to make a better offspring that's better than its ancestors. For Jacob and Renesmee they have the potential to make a super new breed (1/4 human+ 1/4 vampire+1/2 werewolf) just like Leah in that Leah has the potential to create female werewolfs.