What it means

Fertilisation is when an egg and a sperm come together and combine to form the very first cell of an embryo. This is the moment where a new development begins. Before this, the egg and sperm are separate. After this, they become one.

When it’s used

This happens after egg retrieval in IVF. The eggs collected are exposed to sperm in the lab to allow fertilisation to take place. If it is successful, the fertilised egg will begin to grow into an embryo.

Why people get confused

Some people think that once eggs are retrieved, embryos are already created. But fertilisation still needs to happen first. Not every egg will fertilise, and this is one of the earliest points where outcomes can vary.

Think of it this way

Egg retrieval collects the ingredients. Fertilisation is the moment those ingredients actually come together to start something new.

What to expect

After fertilisation, the next step is to see if the cells begin dividing and developing into embryos. Sometimes fertilisation happens, but development does not continue, so this stage often comes with waiting and uncertainty.