What's that movie called...?

In the movie, there is a girl who is about to have a baby or has already had one. At the very beginning it shows her throwing up. On the subway, or something, she sees a chick leave her baby on it. It's a doll actually. The chick takes it home and a bunch of weird stuff happens. At one point, she believes that someone has broken into her house... and is running around the house and stuff. (it's actually herself sort of being mirrored) Anyway, I remember that she found this diary in her house (i think it's new) and eventually, she buries the diary. At one point, she throws the doll in the pool. But she takes it out. At the very end, she buries the doll. Her husband asks where their baby, who was born, I think, she says, "what baby?" And that's it. Does anybody know what this movie was called... I could've sworn Jodie Foster was in it but it doesn't seem like she was...