Treatment
In an antagonist protocol, stimulation starts early in the cycle and an antagonist injection is added after several days to block the natural LH surge. It is shorter than the long agonist protocol, uses fewer injections, and allows an agonist trigger — which is why it is preferred where OHSS risk is high.
Also known as: antagonist protocol, short protocol, cetrorelix protocol
Related Australia guides
Sources
- Royal Australian and New Zealand College of Obstetricians and Gynaecologists (ranzcog.edu.au)
- European Society of Human Reproduction and Embryology (eshre.eu)
Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.