Perhaps there's a way to communicate that Padme is dying? I'm not sure why she would be dying, but that might work.
On the other hand, the fact that her husband is a powerful Sith Lord, apprenticed to the ruler of the Galaxy, who is also a Sith Lord, might be a good reason to send her and the kids into hiding. Adopting Leia doesn't seem so crazy, then, even if Padme isn't dying.