Jugo is a title with the meaning of being equal to sango (sangu), which includes the following three titles: taikotaigo (Emperor's grandmother), kotaigo (Empress Dowager) and kogo (Empress Consort).
准后は、太皇太后、皇太后、皇后の三后（三宮）に准ずるという意味を持つ称号のことである。