Does Embryonic Culture Environment Affect Ploidy Rates in ART Cycles: A Single Center Study in UK

Background: the purpose of the current study was to assess whether embryonic culture conditions has an impact on embryo ploidy in a preimplantation genetic testing for aneuploidy (pgt-a) cycle. methods: in this retrospective single center cohort study, a total of 1099 blastocysts from 278 pgt-a cycles were analyzed. the generated blastocysts were biopsied on days 5 and 6. inseminated oocytes were allocated in different incubators (benchtop and time lapse) and assisted zona hatching was performed on day 3 of embryo development to facilitate the biopsy process which was performed on days 5 and 6 (blastocyst stage). results: the average age across the groups was 38.7±3.6 years and the total number of mature eggs was 2912 which were randomly distributed across both incubators. the euploidy rate obtained from both groups showed a higher proportion of euploid embryos in the tlm incubator (37.03%, 95% ci 31.9-42.1) compared to those cultured in the bt incubator (30.4%, 95% ci 23.1-37.7). regression analysis showed that female age remains to be the key variable driving euploidy rates (0.85, 95% ci 0.82-0.88) although incubator type could be an important covariable (0.54, 95% ci 0.45-0.59). a subgroup analysis of 74 single euploid embryo transfers showed comparable pregnancy and live birth rates. conclusion: this large cohort study demonstrates that uninterrupted controlled culture environment provides increased probability to develop euploid embryo in a pgt-a cycle. however, further evaluation is required to assess how environmental culture conditions at a cellular level could affect epigenetic mechanisms in embryo development and higher aneuploidy rate.