She doesn't (if we're talking about the doll Tiffany), she transfers her soul to the body of Tiffany before Chucky kills the doll of Tiffany (I know it's a little confusing).
To date, Chucky has murdered 30 times including his girlfriend Tiffany, whom he has murdered once as a human and twice as a doll. It is never disclosed how many women that Charles Lee Ray murdered when he was the Lakeshore Strangler, so this body count is strictly after becoming a doll.
Naughtia Childs's birth name is Megan Serbian.
Joshua Childs is 6' 5".
Naughtia Childs is 5' 2".
Tiffany Apan is 5' 4".
Damian Childs was born on July 5, 1974, in USA.
Supposively, Tiffany Espensen is 13 years old and is only 4'9" tall.
Tiffany Sandels is 5' 5".
Tiffany Tisdale is 5' 5".
Tiffany Heft is 5' 5".
Tiffany Coty is 5' 5".
Tiffany Yen is 5' 5".