Fertilisation check

The fertilisation check is done roughly 16–18 hours after eggs are inseminated or injected, when the embryologist looks under the microscope for signs that fertilisation has taken place, most often two visible pronuclei. This single observation determines which eggs will continue in culture and does not by itself predict how an embryo will develop afterwards. Not every mature egg fertilises, and not every fertilised egg develops into a usable embryo; this is a normal part of IVF and is discussed with you as your cycle progresses.

Also known as: fertilisation check, fertilization, egg fertilisation

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.