Fertility Glossary

hCG trigger

A trigger injection using hCG to mature eggs before collection.

Medicines

hCG mimics the natural LH surge. The timing is critical and set by your clinic. Your clinic's protocol and the product leaflet always take priority.

Also known as: Ovitrelle, Gonasi, choriogonadotropin alfa

Related United Kingdom guides

IVF Trigger Injections: Ovitrelle, hCG and Agonist Triggers Explained
Ovitrelle: What It Is and Where It Fits in Fertility Treatment

Related checklists

Trigger Injection Checklist

Planning tools

Trigger Injection Countdown Planner

Sources

NHS — IVF
HFEA — Treatments

Last reviewed: 23 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.

Related terms

Trigger Injection

Injection that matures eggs before collection.

Human chorionic gonadotrophin (hCG)

Human Chorionic Gonadotrophin.

GnRH agonist trigger

A trigger using a GnRH agonist instead of hCG, often to reduce OHSS risk.

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