An IVF trigger shot is a single hormone injection given at the end of ovarian stimulation. It usually contains hCG or a GnRH agonist such as Lupron and pushes the eggs through their final stage of maturity so they can be collected at the right moment.
According to Dr. Mohit Saraogi, IVF Doctor in Mumbai, “The trigger shot looks like a small step in a long cycle, but it decides whether the eggs are ready on retrieval day. Timing matters more than most patients expect. That is why the exact hour is fixed by the doctor and should be followed to the minute.”
Want to understand how a trigger shot is timed within an IVF cycle?
What Does a Trigger Shot Do in IVF?
During stimulation the follicles keep growing, but the eggs inside are not quite finished. That last bit of work is the job of a trigger shot in IVF, and it normally falls to the body’s own natural hormone surge.
Final egg maturation: The injection helps the eggs complete their last stage of development so they can be fertilised in the lab.
Release control: It prepares the follicles to let go of the eggs about 36 hours later, and retrieval is planned just before that so the eggs are collected rather than lost.
A fixed clock: Egg retrieval usually happens 34 to 36 hours after the shot, which is why the time of the injection matters so much.
A stand in for the natural surge: Medicines given earlier in the cycle hold back the body’s own surge, so the trigger takes its place at the right time.
Once the eggs are collected they move on to fertilisation in the lab, as described on our IVF treatment page.
Which Trigger Shots Are Used in IVF?
Two medicines do most of the work and sometimes they are used together. The choice depends on how you responded to stimulation and how likely your ovaries are to overreact.
hCG: This version acts like the natural LH hormone and stays active in the body for several days.
GnRH agonist: Drugs such as Lupron set off the body’s own surge. They are mostly used in antagonist cycles and lower the risk of ovarian hyperstimulation.
Dual trigger: A mix of both is sometimes chosen, especially when earlier cycles gave many immature eggs.
The doctor’s call: Follicle count, hormone levels and past response all play a part, so the choice is never made on preference alone.
The trigger is only one piece of stimulation. Our blog on what foods to avoid during IVF stimulation covers the daily habits that go with it.
What Should You Expect Around the Trigger Shot?
The injection itself takes seconds. What needs care is the timing and the days that follow.
Exact timing: Take the shot at the time the doctor gives you. A gap of even a few hours can affect how mature the eggs are.
Common side effects: Bloating, mild pelvic discomfort and a sore injection site are common and usually settle in a day or two.
A pregnancy test trap: The hCG from the shot can show up on a home test for 10 to 14 days, so testing early can give a false positive.
Warning signs: Severe bloating, fast weight gain, repeated vomiting or very little urine need a call to the doctor straight away because they can point to OHSS.
After retrieval some couples freeze embryos for a later transfer. Our page on frozen embryo transfer after egg retrieval explains how that works.
Key Takeaways: The trigger shot finishes egg maturation and sets the clock for retrieval about 36 hours later. Timing is the part that matters most, so follow the doctor’s schedule exactly. Report any severe bloating or sudden weight gain at once.
Wondering what to ask your doctor about trigger shot timing and the days around egg retrieval?
Frequently Asked Questions
What is an IVF trigger shot?
A hormone injection that finishes egg maturation before retrieval.
When is the trigger shot given?
When the leading follicles reach about 18 to 20 mm in size.
How long after the trigger shot is egg retrieval done?
Usually 34 to 36 hours later.
Does the trigger shot hurt?
Most women feel a brief sting. Some soreness at the site can follow.
Disclaimer:
This blog is intended for informational purposes only and should not be considered a substitute for professional medical advice, diagnosis, or treatment.