Do I have to be present at the birth of my child in atlanta for the child to be given my last name

That depends on how the woman giving birth feels about it.

SHE names the child. If she says you have to be there for the child to get your last name, I'd show up, if I were you.

If she tells you that the child's not getting your last name no matter what---well, you're SOL then.

No