Does the baby have a last name, though? Think about a baby born to parents with different last names. The baby may take the father's last name, the mother's last name, one of at least two different hyphenations, no last name (maybe they think their child will be famous), or an arbitrary last name they make up. And that's assuming they're just plain vanilla "Americans" with no strong ethnic reason for an alternate naming scheme...
It's a placeholder until a name is chosen. It is temporary and expected to be revised. At the hospital I know, the mother's (who carried the baby) full name is selected, e.g. "Baby Jane Doe." Notice no name transformation is required so it generalizes. I don't know what is used in the case of a surrogate mother.
If parents get offended by this straightforward default-naming algorithm, the recommended workaround is to name the baby.
So, now your little ad-hoc substitute-naming scheme has legal ramifications. Good luck getting this to play along with actual letter of the law (at $location1, not to mention $anotherlocation2).
It's not my naming scheme, it's what the hospital I know uses. Can you explain the legal ramifications you are concerned about? The baby does not receive a SSN until it is named by the parents. If the parents were to die before the baby is named, the temporary name used "in the system" doesn't magically become a legal name.
Sorry, I have misunderstood as "this is what I would do." I suppose that's a process descended from the local legal framework, then - as you say, SSN is assigned after name, and the name has some flag meaning "temporary". I would assume there's some handling in place for that eventuality.
(I have seen a different protocol: state ID number is assigned after birth, parents choose name independently of the process, the two are only linked ex post)
