Ulipristal Impurity: (11R,13S,17S)-11-(4-(dimethylamino)phenyl)-5',13-dimethyl-1,6,7,8,11,12,13,14,15,16-decahydro-3'H-spiro[cyclopenta[a]phenanthrene-17,2'-furan]-3,3'(2H)-dione(17-Spyrofuran Impurity).