Both Oocyte Hyperresponse and Oocyte Vitrification Are Safe Procedures Regarding Embryo Euploidy: A Real‐World Study Involving Almost 200 000 Oocytes

Purpose: To ascertain whether ovarian hyperresponse and oocyte vitrification (OV) are associated with an increase in embryo aneuploidy. Methods: Retrospective study involving 197 629 retrieved oocytes. We studied the euploidy rate (ER), the ER according to the number of retrieved oocytes (ERaRO) and according to the number of metaphase II oocytes (MIIO) (ERaMII), and the quotient "MIIO/retrieved oocytes" or mature oocyte rate (MOR). Results: The maximal ERaRO corresponded when only one oocyte was recovered (27% ± 44%), and was somewhat lower when two oocytes were retrieved (14% ± 31%). From the 3rd oocyte until the 36th oocyte, the ERaRO remained constant at around 10%. Regarding MIIO, a similar pattern was observed. For a given number of oocytes, usually the ER was higher if MOR was 100%. Moreover, even when considering only cases with a 100% MOR, the ER was significantly higher in cases where there were 1-2 MIIO. Concerning OV, the regression analysis after adjustment showed that vitrified oocytes had a similar rate of aneuploidy to fresh oocytes. Conclusions: Both ovarian hyperresponse and OV are safe procedures concerning embryo euploidy. The better ER obtained, especially in cases with 1-2 oocytes, opens a new line of research concerning the superior oocyte quality from the point of view of the euploidy of cycles with 1-2 oocytes.