The role of luteinizing hormone in folliculogenesis and ovulation induction.

OBJECTIVE: To review the physiologic, pathophysiologic, and clinical roles of LH in follicle and oocyte development and maturation and to assess the effects of LH content in exogenous gonadotropin preparations used for ovulation induction.
DESIGN: Critical review of the scientific literature devoted to folliculogenesis. Evaluation of comparison studies that used different gonadotropin preparations for ovulation induction. CONCLUSION(S): Folliculogenesis and oocyte maturation are complex processes that require the action of both LH and FSH. Luteinizing hormone is essential to provide the androgen substrate for estrogen synthesis, which in turn contributes to oocyte maturation and may play a relevant role in optimizing fertilization and embryo quality. Although the excessive LH secretion that is present in some disorders is detrimental to reproductive function, this is not applicable to ovulation induction with hMG because this menotropin does not increase daily plasma LH levels. The results of ovulation induction with hMG or FSH-only regimens did not differ in studies conducted in patients with polycystic ovary syndrome and in most studies conducted in ovulatory women undergoing assisted reproductive techniques; conversely, hMG was clearly superior to purified FSH for the treatment of hypogonadotropic hypogonadism. Miscarriage rates were not affected by the use of hMG. Thus, low but detectable LH concentrations positively influence the outcome of ovulation induction in patients with ovulatory disorders and women undergoing assisted reproductive techniques.