Embryology
Blastulation rate describes, for a given cycle, the proportion of fertilised eggs that develop as far as the blastocyst stage by Day 5 or Day 6. It is a laboratory-level statistic used by embryologists and clinics to describe how a batch of embryos progressed, rather than a prediction for any single embryo. Blastulation rates vary between cycles and between people for reasons that are not always fully explained by any one factor, including egg and sperm quality, laboratory conditions and chance biological variation.
Also known as: blastocyst formation rate
Sources
- ICMR Standard Treatment Workflows (icmr.gov.in/standard-treatment-workflows-stws)
Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.