For many women this is where there are more fat cells so even when following a strict diet & training regimen (noting that you can't spot reduce) this will be the last (thus "most stubborn") area to appear to lose body fat because of the higher concentration of fat cells. Above & beyond standard diet & training / cardio, such methods as DNP, clen, ECA, etc. can aid in the reduction of overall body fat, but only liposuction can really actually reduce those specific areas. Even if this is done, then the relative concentrations of remaining fat cells in different places will be where the fat appears to now accumulate if good diet, training, cardio are not continued to be observed.
So, diet, training, cardio. Supplement to aid these and lipo to physically remove it, though fat may start "appearing" in other areas (e.g. remove some fat from hips, it starts looking like your arms or upper stomach or something else now "get fat"). Anti-estrogens such as nolvadex can be used to help reduce the estrogen-specific fat depositing action as well. As with all prescription or otherwise "supplements", care should be taken to understand their purpose and impact on the body, particularly when it comes to the female body and its hormones.