Formal:
* Бебе (bebe) - This is the most common and neutral way to say "baby."
Informal:
* Беба (beba) - This is a more casual and affectionate way to say "baby."
* Младенче (mladenche) - This word is more specific to a newborn baby.
* Дедо (dedo) - This is a term of endearment for a baby, similar to "little one" or "sweetheart."
The best way to use these terms depends on the situation and your relationship with the person you are talking to.