Technically no one "has" to get anything, but you do have a baby shower to hopefully get stuff you need and help with the costs. Some parents/grandparents to be are very involved and will buy tons of stuff and others won't. I have a MIL who wants to buy practically everything and a FIL (they are divorced) who is content picking one thing off the registry and buying only that. It depends on the person, but there is no right or wrong. It's not a like a wedding where it's expected that the brides father pays for it, it's more of an open buy what you want thing, there are no "rules" or traditions to it.