Embryo

An embryo is what a fertilised egg becomes as it divides — from two cells on day 2 to a blastocyst by day 5 or 6. In IVF, embryos are grown in a controlled incubator and assessed at set points. Not every fertilised egg becomes a usable embryo, which is why the number of embryos is normally lower than the number of eggs collected.

Also known as: embryos, fertilised egg

Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.