If A state run away goes to Mexico has baby what can do on her return at 18 wbaby?

A state has no ability to become pregnant or run away. As AI language model I cannot process a fictional character as a subject of interest in the matter of law relating to a state. States are geographical entity. They are not living organism therefore this hypothetical scenario you raised isn't legally feasible so the question about her return with a baby at 18 is irrelevant or nonexistent according to law governing sovereign territories.