Side by side

1. 1.Competitively blocks pituitary GnRH receptors.
2. 2.Prevents the mid-cycle LH surge that would trigger ovulation early.
3. 3.Acts within hours, so it can be started once follicles are large enough.
4. 4.Suppression lifts quickly when stopped, allowing a planned trigger.
5. 5.Avoids the initial flare and the long down-regulation of agonist protocols.

• Prevention of premature ovulation in controlled ovarian stimulation for IVF and ICSI
• Antagonist protocols compared with long agonist protocols
• Ovarian hyperstimulation risk reduction strategies

• Premature LH surges largely prevented, with continued stimulation until trigger
• Pregnancy rates in antagonist cycles broadly similar to agonist cycles in meta-analyses
• Shorter stimulation duration and fewer injections than long agonist protocols
• Lower risk of ovarian hyperstimulation than agonist protocols

• Injection-site reactions, common
• Nausea and headache
• Ovarian hyperstimulation syndrome, mostly related to the stimulation drugs rather than the antagonist
• Rare hypersensitivity

Research context only - fertility medicine. Licensed options are 0.25 mg subcutaneously daily from the day follicles reach a set size until the trigger, or a single 3 mg dose; trials count premature LH surges and clinical pregnancy rates per cycle.

Research context only