The number of autologous, vitrified mature oocytes needed to obtain three euploid blastocysts increases with age.

OBJECTIVE To determine the number of mature oocytes required to make at least three euploid blastocysts DESIGN: Retrospective cohort study SUBJECTS: All patients at a multi-center assisted reproductive technology (ART) practice that warmed vitrified autologous oocytes for IVF from 2011 to October 2023 EXPOSURE: Warming oocytes. MAIN OUTCOME MEASURE(S) Number of mature (MII) oocytes to achieve at least three euploid blastocysts. RESULTS 1,041 thaw cycles from 986 patients were analyzed. Patients were stratified by age at vitrification. Measures of ovarian reserve decreased with advancing age, as expected. Number of mature oocytes (MII) banked and euploid blastocysts available decreased as age at vitrification increased. Patients aged 35-40 used preimplantation genetic testing more than those older than 40 or younger than 35. To optimize the chance of a potential live birth by banking at least three euploid blastocysts, patients less than 35 at vitrification needed a mean of 15 MIIs. This number doubled in patients 38 or older and tripled for patients older than 40. We also analyzed potential live birth per number of MII banked, which also increased with age, with 0.13 expected live births per thawed MII oocyte at less than 35, and 0.04 expected live births if older than 40 at time of oocyte vitrification. Age at vitrification was more influential than indication for vitrification for expected outcome of live birth. CONCLUSION From previously published literature, 3 euploid blastocysts provided a 93% chance of a child. From our analysis, patients required an average of 15 mature oocytes to yield at least 3 euploid blastocysts if they were less than 35 at time of vitrification. The required number of MII doubled in patients aged 38 and older, and tripled in those 40 and older, to achieve the same goal. Given our results, we should encourage egg freeze patients to cryopreserve before age 38. We should also counsel patients that multiple vitrification cycles will likely be required to achieve a high probability of live birth from future oocyte thaws for women aged 38 or older.