Why ovarian stimulation should be aimed to maximize oocyte yield

The ultimate measure of success of assisted reproductive technology (ART) is the cumulative live birth rate (CLBR) per ovarian stimulation cycle, which increases with every oocyte collected. However, the adverse effects of ovarian stimulation on endometrial receptivity, as well as the risks of ovarian hyperstimulation syndrome (OHSS) and adverse obstetric and neonatal outcomes, are observed to increase with ovarian response to stimulation. To mitigate these risks, mild stimulation has been hailed as the safer patient-friendly approach with the additional benefit of cutting the cost of gonadotrophins. Yet accumulating data demonstrate the absence of an adverse effect of ovarian stimulation on oocytes as well as on obstetric and neonatal outcomes, and multiple preventive strategies have been introduced for OHSS. The widespread use of vitrification revolutionized ART by enabling the liberal use of cycle segmentation to minimize the risk of OHSS and avoid impaired endometrial receptivity due to ovarian stimulation. Vitrification also allowed every oocyte to contribute to the CLBR. Thus, it is questionable whether the cost savings from gonadotrophins during the index ovarian stimulation offset the cost saving by preventing repeat ovarian stimulation and repeat laboratory procedures per live birth. This paper aims to prove by contradiction that ovarian stimulation should be aimed to maximize oocyte yield.