Glossary · Definition · v2026.3
What Is Embryo Cleavage?
Embryo cleavage is the series of mitotic cell divisions that occur after fertilization, increasing the number of cells (blastomeres) without increasing overall embryo size.
Clinical significance
Embryologists monitor cleavage rate and symmetry as indicators of embryo quality. A normally cleaving embryo typically reaches 2 to 4 cells by Day 2 and 6 to 8 cells by Day 3. Delayed or arrested cleavage may indicate chromosomal abnormalities or poor developmental potential.
Common confusion
Cleavage refers to cell division only, not cell growth. The embryo does not increase in size during cleavage: the same volume is partitioned into progressively smaller cells.
Related reference
Used in
This content defines terminology for educational orientation. It does not constitute medical advice.
IVF Daddies Newsletter
Structural briefings on policy, clinical, and regulatory developments.
Weekly updates on family-building governance.