RESUMEN
The authors review the physiology of the ovulatory cycle and the role of the gonadotrophins in ovulation induction in patients with anovulatory disorders and in multifollicular development for assisted reproductive technologies. The use of gonadotrophins with luteinizing hormone (LH) activity and the use of recombinant LH associated with follicle stimulating hormone (FSH) are discussed. The authors point out that administration of gonadotrophins with LH activity is essential in hypogonadotropic hypogonadal anovulation, and data available in the medical literature allow the conclusion that recombinant LH may be added to all ovarian stimulation protocols because it is difficult to determine which patients will benefit from LH administration and there is no evidence that LH affects adversely the outcome of ovarian stimulation. The use of recombinant LH in addition to recombinant FSH may be particularly useful when a GnRH antagonist is associated with the ovarian stimulation regimen, by preventing the fall in estradiol and diminishing FSH requirements.