FROM OOCYTES TO A LIVE BIRTH: DOES PGT-A HELP OR HARM?

*University of Miami, UHealth Center for Reproductive Medicine, Miami, Florida Limited data exists on the number of oocytes needed to achieve a live birth (LB) and women often ask how many oocytes are sufficient to achieve a LB1. Having age specific data on LB rates (LBR) based on number of oocytes is crucial for appropriate counseling on risks and benefits of oocyte retrieval and its prognosis2. A previous study published in 2009 examined the biological efficiency of oocytes by determining how many it took to achieve a LB. In that study the efficiency of IVF was examined by analyzing the LBR in fresh embryo transfers and estimating the LBR from the remaining frozen embryos based on number of oocytes retrieved3. With the advent of vitrification and increased use of preimplantation genetic testing for aneuploidy (PGT-A), we performed an updated analysis to evaluate the possible improved LBR per oocyte retrieved. To investigate the LBR in relation to the number of oocytes retrieved during IVF. This retrospective cohort study included all cycles between the years 2014 and 2019, where patients’ own oocytes and the resulting embryos were fully utilized (fresh and vitrified blastocysts). We excluded cycles with remaining frozen embryos and donor oocyte cases. Data on number of oocytes retrieved, number of embryos obtained and transferred (fresh and frozen), use of PGT-A and total number of LB was obtained. The LBR was calculated based on this data. A total of 16,698 retrievals were performed generating a total of 178,632 oocytes and 16,415 embryos. Of those embryos, 4065 underwent trophectoderm biopsy for PGT-A. The remaining 12,350 did not. The average number of oocytes retrieved was 10.70 (9.9 in the non-PGT-A group and 13.3 in the PGT-A group) (see Table 1). The total LB were 6,105 (4,490 in the non-PGT-A group and 1,615 in the PGT-A group). There was a marked decrease in LBR with advancing age. Overall, the LBR per oocyte was higher in the non-PGT-A group than in the PGT-A group (3.61% vs. 2.98% respectively, p<0.05). When stratified by age, this difference was most pronounced in the under 35 age group (4.5% non-PGT-A vs 3.5% PGT-A, p<0.01). We re-examined our data similarly to the data previously published in 20093. During IVF, approximately 3.42% of oocytes produce a LB, a rate similar to the one obtained in 2009. Interestingly, the overall LBR per oocytes retrieved in the PGT-A was significantly lower than in the non-PGT-A group. This difference was most notable in the under 35 age group, suggesting that PGT-A may negatively impact outcomes in younger women.