What Is a Trigger Shot in IVF? 

If you’re going through in vitro fertilization (IVF) or another form of assisted reproductive technology (ART), you may hear your fertility specialist mention a “trigger shot.” But what is a trigger shot in IVF, and why is it such an important part of the IVF process?

What Is a Trigger Shot in IVF?

A trigger shot is an injection of medication, usually human chorionic gonadotropin (hCG) or a GnRH agonist, used to stimulate the final maturation of eggs and trigger ovulation at a precisely timed point. It plays a vital role in preparing your body for the egg retrieval step of IVF.

During a natural menstrual cycle, your body releases a surge of luteinizing hormone (LH) to trigger ovulation. In an IVF cycle, where hormone levels are tightly controlled, the trigger shot mimics this natural LH surge and ensures your eggs are mature and ready for retrieval.

Why Is the Trigger Shot So Important in IVF?

The success of your egg retrieval depends heavily on the proper timing and effect of the trigger shot. If administered correctly, the trigger shot ensures:

• Final maturation of the eggs inside the ovarian follicles
• Controlled timing of ovulation so your fertility team can retrieve eggs before they’re released naturally
• Optimal conditions for fertilization, whether using traditional IVF or ICSI

Failing to administer the trigger shot properly, or missing the precise timing, can lead to immature eggs or missed ovulation, which may cancel the IVF cycle.

When Do You Take the Trigger Shot?

Your fertility provider will give you very specific instructions about when to take your trigger shot. It’s typically administered:

• About 36 hours before your scheduled egg retrieval
• Often late in the evening or at night
• Exactly as instructed to align with your body’s ovulation window

Because timing is everything, patients are often asked to set alarms or even have support from a partner or nurse to ensure the shot is taken at the exact time needed.

What Medications Are Used for the Trigger Shot?

There are a few different types of medications that may be used as an IVF trigger shot:

Your fertility team will select the best trigger shot based on your hormone levels, follicle count, and overall response to IVF stimulation medications.

What Happens After the Trigger Shot?

Once the trigger shot is given:

• Your body begins the final maturation process of the developing eggs
• Ovulation will occur naturally about 36 to 40 hours later if retrieval is not done
• You’ll return to the fertility clinic for egg retrieval, usually scheduled around 36 hours after the injection, before ovulation occurs

During this window, your fertility specialists will retrieve mature eggs from the ovaries under light sedation. These eggs will then be fertilized in the lab as part of the next step in your IVF cycle.

The Trigger Shot Is a Key Milestone in IVF

While it may feel like just one more injection in a series of many, the trigger shot is one of the most critical steps in the IVF process. It ensures your eggs are ready, your timing is right, and your chances of a successful retrieval, and ultimately, pregnancy, are optimized.

If you have questions about your trigger shot timing, medication, or how to administer it, always reach out to your fertility care team. We are here to guide you through every step to help make your IVF journey as smooth and successful as possible.