Deconstructing the myth of poor prognosis for fast-cleaving embryos on day 3. Is it time to change the consensus?

• Published in: Journal of assisted reproduction and genetics 2019-11, Vol.36 (11), p.2299-2305
• Main Authors: Pons, Maria Carme, Carrasco, Beatriz, Parriego, Mònica, Boada, Montserrat, González-Foruria, Iñaki, Garcia, Sandra, Coroleu, Buenaventura, Barri, Pedro N., Veiga, Anna
• Format: Article
• Language: English
• Subjects: Adult; Assisted Reproduction Technologies; Birth Rate; Blastocyst - physiology; Blastocysts; Consensus; Embryo Culture Techniques - methods; Embryo Implantation - physiology; Embryo Transfer - methods; Embryonic Development - physiology; Embryos; Female; Fertilization in Vitro - methods; Gynecology; Human Genetics; Humans; Medicine; Medicine & Public Health; Middle Aged; Pregnancy; Pregnancy Rate; Preimplantation Diagnosis - methods; Prognosis; Reproductive Medicine; Retrospective Studies; Statistical analysis; Young Adult
• ISSN: 1058-0468; 1573-7330
• DOI: 10.1007/s10815-019-01574-y

Purpose To determine the developmental competence of fast-cleaving D3 embryos. Methods Retrospective study including 4028 embryos from 513 PGT-A cycles performed between July 2014 and June 2017. Embryos were cultured in time-lapse incubators and biopsied at blastocyst stage. Embryos were classified in groups according to the number of cells on D3 (from 2-cell to ≥13 -cell and compacted). A generalized linear mixed model adjusted for confounding factors was performed to assess the chance to give rise to an euploid blastocyst in each group compared with the chance of 8-cell embryos. Implantation and live birth rates were also analyzed. Results The statistical analysis showed that embryos with 9 to 11 cells had a slightly lower euploid blastocyst rate than 8-cell embryos (OR (95% CI) 0.77 (0.61–0.96)) while embryos with more than 11 cells were found to be just as likely to give rise to an euploid blastocyst as the 8-cell embryos (OR (95% CI) 1.20 (0.92–1.56)). Conversely, slow-cleaving embryos had a significantly lower euploid blastocyst rate than 8-cell embryos (OR (95% CI) 0.31 (0.24–0.39)). Moreover, euploid blastocysts derived from fast-cleaving embryos and from 8-cell embryos exhibit similar live birth rates. No significant differences were found in the chance to give rise a live birth between 8-cell and 9- to 11-cell embryos (OR (95% CI) 1.23 (0.70–2.15)) and > 11-cell embryos (OR (95% CI) 1.09 (0.57–2.09)). Conclusions Embryos with more than 11 cells exhibit similar developmental competence to 8-cell embryos. Their poor prognosis should be reconsidered.