What's this movie called?

I remember watching a movie a while back, it was probably made in the nineties or so, and Renee Zellweger was one of the actresses in it. It was about this abducted pregnant woman and she was forced to stay with a man and his girlfriend (Renee) and I guess they just wanted her baby. In the end I'm pretty sure she ends up killing them and having her baby. Does anyone know the name of this movie?