Euploid day 7 blastocysts of infertility patients with only slow embryo development have reduced implantation potential

Research question: What is the reproductive potential of embryos that achieve blastulation on day 7 followed by preimplantation genetic testing for aneuploidies (PGT-A) for infertility patients with slow embryo development? Design: This was a retrospective cohort study in a private IVF clinic of consecutive female infertility patients (n = 2966) aged 24-48 (36.3 +/- 3.8) years who underwent frozen embryo transfer (FET) of a single euploid blastocyst. Results: The women underwent single euploid FET of an embryo that achieved blastulation on day 5 (n = 1880), day 6 (n = 986) or day 7 (n = 100). Day 7 embryos resulted in lower implantation and live birth rates compared with both day 5 and day 6 embryos (P < 0.001). The day 5, day 6 and day 7 groups had 68.5%, 55.2% and 36.0% live birth rates, respectively. The day 7 group was older than the day 5 group (P < 0.001); comparing age-matched cohorts, the day 7 group still had lower implantation and live birth rates (P < 0.0001 and P < 0.001, respectively). Embryo grade was unrelated to live birth rates. Day 7 embryos of expansion grade 5 or 6 or trophectoderm grade A were more likely to be euploid compared with expansion grade 3 or trophectoderm grade B. Conclusions: Euploid day 7 embryos represented reduced implantation potential, even when controlling for maternal age. Of all day 7 embryos that underwent PGT-A, euploidy was associated with expansion grade 5 or 6 and trophectoderm grade A. These results can help providers manage patient expectations in cases where infertile women have slow embryo development.

Automated summary

This study investigated the reproductive potential of embryos that undergo preimplantation genetic testing for aneuploidies (PGT-A) in infertility patients with slow embryo development. The study found that day 7 embryos resulted in lower implantation and live birth rates compared to day 5 and day 6 embryos. Day 7 embryos with expansion grade 5 or 6 and trophectoderm grade A were more likely to be euploid. These findings can help manage patient expectations in cases of slow embryo development.