What it means

A cleavage stage embryo is an early stage of embryo development, usually around day 2 to day 3 after fertilisation. At this point, the embryo is made up of a small number of cells that are actively dividing.

When it’s used

This term comes up after fertilisation, when the lab monitors how embryos are growing before they reach the blastocyst stage. Some transfers may also happen at this stage, depending on the plan.

Why people get confused

Some people think an embryo is only meaningful at the blastocyst stage. But development starts earlier, and cleavage stage is part of that process. Not all embryos will continue growing to later stages.

Think of it this way

If fertilisation is the starting point, the cleavage stage is the early growth phase where the embryo begins dividing and forming more cells.

What to expect

After fertilisation, embryos are observed over the next few days. Some will continue dividing, while others may stop developing. This stage is one of the early points where differences in development start to appear.