Failed fertilisation

Failed fertilisation means that none, or very few, of the eggs collected in a cycle show signs of normal fertilisation at the fertilisation check. It can happen with either conventional IVF or ICSI and may relate to egg maturity, sperm function, or factors that are not always identifiable from a single cycle. When this happens, the embryology and clinical team will usually discuss what was observed and whether options such as ICSI, rescue ICSI or assisted oocyte activation may be relevant for a future cycle. A single cycle of failed fertilisation does not necessarily predict the outcome of a later attempt.

Also known as: fertilisation failure, no fertilisation, zero 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.