A goof?

(Spoilers):
So at the beginning of the film, Julie says to Nick that she had something to tell him, but we never find out because she dies in a car crash.
Nick goes back in time to that same place to save her, and their new future looks bright.
Then towards the end when he goes back to that exact spot again, we finally figure out what this seriously secret thing is which turns out that Julie is pregnant.
So where was the baby in the universe when Nick saves her?