expression, ichidan verb
to be a chatterbox from birth; to be born talking
Derogatory idiomatic expression used to criticize someone who talks excessively, as if their mouth came out before the rest of them at birth. The literal meaning is 'to be born mouth first'.
あの人は口から先に生まれたような人だ。
That person seems like they were born talking.
口から先に生まれたのかと思うほどよくしゃべる。
He talks so much you'd think he was born mouth first.