The slang usage of gone meaning pregnant is mainly a BrE one according to
Cambridge Dictionary (mainly UK informal) pregnant:
How far gone is she? (= How long has she been pregnant?)
while Collins Dictionary and The American Heritage Dictionary state that it is also an AmE usage
(US, slang) pregnant:
She is two months gone.
I couldn’t find other details about this usage so I’d like to ask:
Is gone meaning pregnant originally a BrE expression which later spread to AmE?
What sense of gone conveys the meaning of pregnant here?
How recent is this usage?