Boo boo

Where does the phrase "Boo boo" come from? I.e. To a child: "Do you have a boo boo?"

Thought: does it referance a blister known as a "bubo" is in the bubonic pluage?

What is a 'boo boo'? It's not something I'm familiar with.

Without knowing what it actually means, it's hard to speak with real confidence, but my instincts tell me it's unlikely to derive from 'bubo'.

DFG