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Fertility Glossary

Long agonist protocol

An older IVF protocol that suppresses the pituitary before stimulation begins.

Medicines & protocols

A GnRH agonist is started in the preceding cycle to down-regulate the pituitary, after which stimulation begins. It takes longer and can cause temporary menopausal symptoms, but remains useful in selected situations such as some cases of endometriosis.

Also known as: down-regulation, long protocol, GnRH agonist protocol

Related Canada guides

Sources

  • Canadian Fertility and Andrology Society (CFAS)

Last reviewed: September 9, 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.

Related terms

GnRH agonist

A medication that first stimulates then suppresses the pituitary.

Antagonist protocol

The most common IVF protocol, using a GnRH antagonist to prevent early ovulation.

Controlled ovarian stimulation

Injectable hormones used in IVF to grow several follicles at once.

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