I'm going to assume, that since this discussion is rooted in issues in BD, that it is alright to post something with BD spoilers.
I don't know if Leah can have children. Overall, I think it unlikely. She has a point- why is she the only female wolf? In all of their history, she's the first one. Obviously girls have the genes, and not just as carriers. It isn't like Bella and Edward, when it's possible only because Edward doesn't kill her first, like any other vampire would have. It isn't a case of women not surviving the change, it's the fact that they never change at all.
However, there is still hope for her to imprint, because of Jacob. He imprinted on someone who is definitely not Quileute. Leah might still have a chance. That's slightly off topic, but it fits together in my mind with this one when I think about Leah.
Someone can lose their period from stress, be it mental, emotional, or physical, and I think Leah has had quite a lot of that, from Sam, to losing her father, to becoming a werewolf, the last of which being an extreme physicaal stress. If she stopped phasing, she might have a chance of going back to it. Besides, what child could handle changing from wolf form to human form and vice versa? It might be a protection, not only for her, but for any children she could have, particularly when she can't control her phasing.
Team Rosalie, Team Esme, Team Emmett, Team Carlisle, Team Jacob, Team Leah, Team Charlie, Team Angela...
Dang. Why don't they make a Team Everyone?