13,14-dihydro Prostaglandin F2α (13,14-dihydro PGF2α) is the analog of PGF2α which has no unsaturation in the lower side chain. It causes luteolysis in hamsters with a potency five times higher than PGF2α. The ED50 value for 13,14-dihydro PGF2α as a luteolytic agent in hamsters is 1.5 µg/100 g.[1]