hCG Trigger Injection

An hCG trigger injection helps complete egg maturation and schedules ovulation or egg collection. It is a hormone medicine given near the end of an ovarian stimulation plan and provides a signal similar to the body’s natural luteinising hormone surge.

The injection is time-sensitive. The clinic chooses when it should be given after reviewing follicle growth and other monitoring results. The planned procedure or intercourse timing is then arranged around that instruction. hCG can also be detected by pregnancy tests, so testing too soon after the injection may be confusing.

The hCG trigger may be used during [Ovarian Stimulation](/treatments/fertility-and-assisted-reproduction/ovarian-stimulation/) when follicles have reached the stage selected by the fertility team. The same medicine can be used in plans involving timed ovulation or egg collection, but the schedule and follow-up differ between patients.

A specialist may choose another trigger medicine or a different timing strategy. The choice can reflect the risk of an excessive ovarian response, the planned procedure, hormone results, and the clinic’s protocol. Only the fertility team should change the trigger, because a timing change can affect the treatment schedule.

You may receive a precise clock time for the injection and separate instructions for the appointment that follows. Injection-site soreness, headache, nausea, or pelvic discomfort can occur. Seek prompt advice for severe abdominal pain, rapidly increasing bloating, vomiting, breathing difficulty, faintness, or reduced urination. Ask how to record the dose and what to do if timing is missed.

The hCG trigger is a single planned step in a fertility cycle, not a long-term treatment. Follow the supplied storage and injection instructions and keep the clinic’s contact details available. Tell the team about medicines, allergies, and new symptoms. Because hCG may affect pregnancy-test results for a period after treatment, ask when testing will be meaningful.