One from the Dead’s repertoire which never really made it in the studio, Bertha is a favorite at shows. The eponymous “Bertha” has been rumored to be a big floor fan that was located in the Dead’s office. Robert Hunter has dispelled this rumor saying:

No, this was after the fact. I don’t know where that story … I think they started calling this fan in the office that would run around and try and catch everyone and cut their fingers off. They started calling it Bertha. But no, this is not true. Bertha, I think, is probably some vaguer connotation of birth, death and reincarnation. Cycle of existences, some kind of such nonsense like that. I wouldn’t be surprised, but then again, it might not be. I don’t remember.

So “Bertha” might be a play on the word birth.