I-36: The Role of LH in Controlled Ovarian Stimulation

It is known that the follicular selection and final stages of follicular maturation are equal if not more dependent on low circulating levels of LH.In addition to stimulating production of thecal androgens as substrate for estrogen synthesis, LH stimulates granulose cell via LH receptors induced by FSH and estrogen in larger but not smaller follicles. The data from numerous assisted reproduction studies confirm that most patients will respond to gonadotropin preprations containing only FSH.However, 10-12 % of patients may fail to respond adequately to this type of ovarian stimulation.Presumably these patients lack adequate concentrations of endogenous LH after pituitary down-regulation and would benefit from the addition of LH to ovarian stimulation. Specific subgroups of women may benefit from LH activity supplementation, patients > 35 years,in those showing an initial abnormal ovarian response to r-hFSH monotherapy,and in low prognosis women treated with GnRH antagonists and clearly patients with hypogonadotrophic hypogonadism require exogenous LH to achieve optimal assisted reproductions outcomes. Exogenous LH supplementation was consistently with higher peak estradiol concentrations.The use of hMG in long GnRH agonist cycles was associated with a 3-4 % increase in live birthrate.The advent of recombinant gonadotrophins brought significant changes in fertility therapy. Over a decade,recombinant LH (rLH) has been used for clinical trials and the amount of peripheral LH that is necessary for optimal follicular growth,oocyte maturation,subsequent embryo development and assisted reproduction outcomes during ovulation induction can now be better evaluated. The assisted reproduction practioner should always bear the importance of adequate LH stimulation in mind.Future research should focus on good method for identifying patients most likely benefit from LH supplementation.