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Fertility Glossary

LH surge

The sharp rise in luteinising hormone that triggers ovulation.

Hormones

The LH surge is a short, steep rise in luteinising hormone that causes the dominant follicle to release its egg roughly 24 to 36 hours later. Ovulation predictor kits look for this surge. In IVF the surge is usually suppressed with medicine so that eggs can be collected at a planned time.

Also known as: luteinising hormone surge, LH peak

Related South Africa guides

Sources

  • ESHRE/ICMART glossary of assisted reproductive terminology

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.

Related terms

LH (luteinising hormone)

The pituitary hormone whose surge triggers ovulation.

Ovulation

The release of a mature egg from an ovary, usually once each cycle.

GnRH antagonist

A medicine that blocks the LH surge quickly, usually started mid-stimulation.

Premature ovulation

Releasing eggs before they can be collected.

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