Current concepts and novel applications of LH activity in ovarian stimulation.

Luteinizing hormone (LH) is a crucial physiological regulator of the human menstrual cycle. LH activity is also contained in many medications used to treat anovulation and to stimulate multiple folliculogenesis for assisted reproduction techniques. However, LH activity had previously been regarded as just a contaminant of follicle-stimulating hormone (FSH)-containing products and deemed potentially detrimental for reproductive function. Novel experimental and clinical evidence now suggests that the administration of pharmacological amounts of LH activity, instead of being harmful, is therapeutically advantageous, particularly in the support and modulation of ovarian folliculogenesis. The aim of this article is to provide an overview of the effects of LH activity administration in ovarian stimulation and to outline novel unconventional gonadotropin regimens that might improve the efficacy, safety and convenience of ovulation induction.