Why do we Modify Ovarian Stimulation Protocols when Repeating a Cycle?” Is it a Scientific Issue, An act of Faith, or a Lack of Trust?

Abstract

Ovarian Stimulation (OS) is a cornerstone and indispensable step in reproductive medicine. The aim of OS is to induce the growth and maturation of multiple follicles to collect an adequate number of oocytes. The availability of a sufficient number of mature oocytes suitable for in vitro fertilization (IVF) significantly enhances the likelihood of successful fertilization, the development of high-quality euploid embryos, and ultimately, the achievement of a successful pregnancy. Frequently, it becomes necessary to repeat an ovarian stimulation procedure in a patient. In some instances, when faced with a poor ovarian response, the strategy of oocyte accumulation is employed to increase the chances of having a euploid blastocyst available for transfer. Moreover, even among good responders, there are occasions where it becomes necessary to repeat a cycle due to a prior unsuccessful attempt. The present study shows that there is a great variability in ovarian response in successive ovarian stimulation procedures, even administering the same protocol, both in terms of doses and medications. Thus, repeating an ovarian stimulation procedure does not necessarily entail the need to modify the stimulation protocol. There is variability in ovarian response even when the same gonadotropins are administered, as shown in the present study. Hence, in consecutive stimulations, variations in the response are physiological, even though the same protocol and medication are employed. Selecting one protocol over another should prioritize the comfort and convenience of the patient rather than a hypothetical improved response with different medications.