Novel protocols for ovarian stimulation

Increased knowledge of the mechanisms of single dominant follicle selection has led to the development of a novel and effective ovulation induction regimen for anovulatory women - the step-down protocol aiming at inducing single dominant follicle growth. A major improvement to this approach would be the ability to use initial screening characteristics to assess the individual FSH threshold beforehand. In contrast, in IVF, interfering in the process of single dominant follicle selection in ovulatory women by late follicular phase administration of low doses of FSH may result in the development of a safer, shorter, and cheaper means of stimulating the ovary. Such a regimen would result in a reduced number of oocytes available for IVF as compared with presently applied stimulation protocols. Further studies are required to establish convincingly whether oocyte quality and subsequent capacity to be fertilized and to form good-quality embryos are improved when less follicles are stimulated, and whether the avoidance of excessive ovarian stimulation may impact positively on endometrial receptivity and improve implantation rates. The application of minimal stimulation protocols will result in a significantly reduced duration of stimulation and significantly lower amounts of exogenous FSH preparations. Less monitoring will be required, and the chances for short-term complications or long-term risks may be reduced. Although this approach is likely to render IVF more cost effective, the potential benefits of minimal stimulation protocols remain to be confirmed in large series of patients.