Congratulations on your new baby girl in spanish
¡Felicitaciones por el nacimiento de su bebé niña!
(Translation: Congratulations on the birth of your baby girl!)
Other ways to express congratulations on a new baby girl in Spanish:
Note: "Enhorabuena" is a more formal way to say "congratulations", while "Feliz nacimiento" is a more casual way to express congratulations on a birth.