What are acceptable benchmarks for fertilisation and blastulation rates?

[Verified against the Vienna Consensus 2017] Fertilisation, IVF. Normal fertilisation rate — 2PN and 2PB assessed at 17 ± 1 h post-insemination, as a function of all cumulus-oocyte complexes inseminated: competency ≥60%, benchmark ≥75%. The benchmark was derived by rounding the product of the benchmark MII oocyte rate (90%) and fertilisation rate of MII oocytes (80%). Blastulation. Blastocyst development rate, defined as blastocysts at 116 ± 2 h post-insemination per normally fertilised oocyte: competency ≥40%, benchmark ≥60% on Day 5. A further 10–15% may develop by Day 6 (140 ± 2 h). Good blastocyst development rate, Day 5: competency ≥30%, benchmark ≥40%, with an additional 5–15% by Day 6 depending on culture system. Three points that determine whether your numbers are comparable to these at all: The denominator is normally fertilised (2PN) oocytes, not cleaved embryos. Using cleaved embryos inflates the figure and makes it non-comparable. The timing is specified. Assessment outside 116 ± 2 h changes the result — embryos assessed late will appear to perform better. Day 5 assessment is preferred over Day 5/6 combined, for consistency with prior consensus and because of limited embryo numbers on Day 6. Named confounders: timing of laboratory observation, culture medium, and culture conditions — pO2 concentration in particular. Blastocyst quality is graded on blastocoele expansion, trophectoderm and inner cell mass. Of these, trophectoderm was the statistically significant independent predictor of live birth after adjustment for confounders.