It seems, therefore, that in PCOS patients stimulated for IVF with HMG, follicular-phase LH levels have an adverse effect on follicle and oocyte numbers as well as on oocyte quality. Moreover, an inappropriately raised LH appears to have a deleterious effect on the pregnancy outcome by being associated with a greater possibility for miscarriage. On the other hand, the administration of GnRH-a in the long desensitization protocol seems to reverse the detrimental effect of increased LH concentrations on follicular and oocyte development, whereas the beneficial effect on oocyte maturity, although significant, appears to be less profound. Furthermore, GnRH-a administration is associated with a decreased risk for early abortion.