OBJECTIVE: Current data suggests that LB following transfer of a euploid embryo (EE) is independent of age or type of ART treatment. At our center, OC is routinely performed and trophectoderm biopsy-preimplantation genetic screening (TEBX-PGS) is now being used in conjunction with autologous OC thaw (AOCT) cycles. From our novel data, we estimated the no. of MII oocytes required to achieve LB at different ages.
DESIGN: Retrospective study and theoretical model
MATERIALS AND METHODS: Data from 152 patients (202 retrievals, 167 thaws) who underwent AOCT with intended TEBX-PGS aged 25-40y were reviewed. To calculate the no. of MII oocytes needed to achieve one EE the following data were assessed: total no. of MII oocytes that survived, 2-pronuclear (2PN) fertilization, development to BL, BL achieving quality for TEBX, and BL ploidy status after TEBX-PGS. The no. of MII oocytes needed to achieve one EE was calculated as no. MII thawed/EE. Because combining these technologies is relatively new, many pregnancies are currently ongoing (ONG). Thus "LB" included >1st trimester ONG pregnancies and babies born (BB), with the LB rate calculated as total no. ONG+BB/EE transferred. The theoretical no. of MII oocytes needed for one LB was then calculated as no. thawed MII needed to achieve one EE/LB rate per EE.
RESULTS: See Table. Of the 1,839 MII oocytes that survived, 2PN fertilization rate was 75% and of those, 50% formed BL. 83% of BL were suitable for TEBX. The no. of MII oocytes needed to achieve one EE was 8, 12, and 13 for age groups of 25-34y, 35-37y, and 38-40y; LB rate per EE was 59.8% across all ages. Thus, the no. of MII calculated to achieve one LB was 13, 19, and 22 in the age groups, respectively.
CONCLUSIONS: EE have a relatively uniform efficiency and therefore, achievement of an EE after OC, thaw, and fertilization can help to estimate the theoretical no. of cryopreserved MII oocytes required to achieve a LB. One criticism of OC is that it provides women with a false sense of security; because of varying cycle outcomes, OC cannot guarantee future birth. Our findings serve as a counseling tool by providing women with realistic expectations of OC outcomes at our center.