You have been doing injections for 8-12 days. You have had multiple monitoring scans. Your follicles are the right size. And then your doctor says: "We're triggering tonight. Take the shot at exactly 10:30 PM."

Not 10 PM. Not 11 PM. Exactly 10:30 PM.

This is the trigger shot — the single most time-critical moment in your entire IVF cycle. It is the injection that sets the clock for egg retrieval, and if the timing is wrong, the consequences are real.

This article explains what the trigger shot is, why timing is so precise, what types exist, how to give it, what side effects to expect, and what happens if something goes wrong.

What the Trigger Shot Actually Does

During ovarian stimulation, your follicles grow and the eggs inside them mature. But the eggs are not yet ready to be retrieved — they need one final push to complete their maturation process.

The trigger shot provides that push. It mimics or triggers the natural LH surge that your body would produce before ovulation.

Here is the timeline after injection:

Time After Trigger | What Happens

0 hours | Trigger shot is administered

0-12 hours | Final egg maturation begins inside the follicles

12-24 hours | Eggs complete meiosis (chromosomal division) — becoming mature (MII) eggs

24-36 hours | Eggs are mature and ready for retrieval

36-40 hours | Ovulation begins — eggs start releasing from follicles

40+ hours | Eggs have ovulated — they are no longer retrievable from follicles

The retrieval window is 34-36 hours after the trigger. This is why your doctor gives you an exact time — they are scheduling your retrieval for 34-36 hours later, and they need the eggs to be mature but still inside the follicles.

  • Too early (before 34 hours): Eggs may not be fully mature. Immature eggs cannot be fertilised.
  • Too late (after 40 hours): Eggs may have already ovulated. An empty follicle at retrieval means no egg.

Types of Trigger Shots Available in India

1. hCG Trigger (Most Common)

Brand | Type | Route | Approximate Cost

**Ovidrel** (choriogonadotropin alfa) | Recombinant hCG | Subcutaneous (belly) | ₹2,500-₹4,000

**Pregnyl** | Urinary-derived hCG | Intramuscular (buttock) | ₹500-₹1,500

**Ovitrig/Fertigyn** | Urinary-derived hCG | Intramuscular | ₹300-₹1,000

How it works: hCG (human chorionic gonadotropin) is structurally similar to LH and triggers the same cascade — final egg maturation followed by ovulation.

Advantages: Well-established, effective, and the standard trigger for most IVF cycles.

Risk: hCG can worsen Ovarian Hyperstimulation Syndrome (OHSS) in high-risk patients because hCG stays in the body for days, continuing to stimulate the ovaries.

2. GnRH Agonist Trigger (For High OHSS Risk)

Brand | Route | Approximate Cost

**Lupride/Leuprolide** (GnRH agonist) | Subcutaneous | ₹200-₹800

How it works: Instead of providing hCG directly, it causes a natural LH surge from the pituitary gland. This LH surge is shorter-lived than hCG, which reduces OHSS risk.

When it's used: Patients at high OHSS risk — typically those with PCOS, high AMH (>5 ng/mL), or many developing follicles (>20).

Important note: GnRH agonist triggers can only be used if you are on an antagonist protocol (not an agonist/long protocol). Your doctor will determine this.

Risk: Slightly higher rate of "empty follicle syndrome" and potentially lower egg maturity. Some doctors use a dual trigger (low-dose hCG + GnRH agonist) to balance OHSS risk with egg maturity.

3. Dual Trigger

A combination of GnRH agonist + low-dose hCG (1,000-1,500 IU instead of the standard 5,000-10,000 IU). This provides the benefits of both — good egg maturity with reduced OHSS risk. Increasingly popular in India for moderate-risk patients.

How to Give the Trigger Shot: Step by Step

If Subcutaneous (Ovidrel, Lupride)

The technique is the same as your daily stimulation injections:

  1. 1Check the time. You should give the shot within 15-30 minutes of the prescribed time. If your doctor said 10:30 PM, the acceptable window is 10:15-10:45 PM.
  2. 2Wash hands.
  3. 3If using Ovidrel pre-filled syringe: Remove the cap, clean the injection site (lower abdomen) with an alcohol swab, pinch the skin, inject at 45-90 degrees, push the plunger slowly, hold for 5 seconds, withdraw.
  4. 4If using Lupride from a vial: Draw the prescribed dose into a syringe, clean the site, inject subcutaneously.

If Intramuscular (Pregnyl, Fertigyn)

  1. 1Mix the medication: These usually come as a powder with a diluent. Inject the liquid into the powder vial, swirl gently until dissolved, draw the mixed solution back.
  2. 2Injection site: Upper outer quadrant of the buttock.
  3. 3Use the longer IM needle provided.
  4. 4Insert at 90 degrees into the muscle, aspirate (pull back slightly — if blood appears, withdraw and try a new spot), inject slowly, withdraw and press with gauze.
  5. 5This is harder to self-administer. Having your partner or a nurse do it is perfectly fine.

The Timing Protocol: How to Get It Right

Your clinic will call or message you with specific instructions that look something like this:

"Trigger tonight at 10:30 PM. Egg retrieval is scheduled for Thursday at 8:30 AM."

Here is how to ensure you do not miss it:

Set Multiple Alarms

  • Alarm 1 (30 minutes before): On your phone. Label it: "Prepare trigger shot — get medication out, gather supplies."
  • Alarm 2 (at the exact time): On your phone. Label it: "GIVE TRIGGER SHOT NOW."
  • Alarm 3 (at the exact time): On your partner's phone. As backup.
  • Alarm 4 (15 minutes after): On your phone. Label it: "Confirm trigger shot was given."

Other Precautions

  • Do not take the shot early because it is "more convenient." If the doctor said 10:30 PM and you want to go to bed early, that is not a reason to take it at 9 PM. The retrieval is timed to your trigger. Changing the trigger time by an hour changes the optimal retrieval window by an hour.
  • Keep the medication accessible. If it needs refrigeration, take it out 15-20 minutes before the injection time. Do not leave it in a bag you might forget somewhere.
  • Do not travel on trigger day. Be at home or in a stable environment. This is not the day to be stuck in traffic wondering whether you will make it home in time.
  • Confirm the dose with your clinic if you have any doubt. Read back the medication name and dose to the nurse when they call.

What Happens If You Miss the Trigger

This is the question everyone fears. Here is the honest answer:

Situation | What Happens | What to Do

**Less than 1 hour late** | Usually fine. Eggs may still be in the maturity window at retrieval | Give the shot immediately. Call the clinic to inform them — they may shift retrieval by 30-60 minutes

**1-3 hours late** | Retrieval timing may need adjustment. Eggs may still be retrievable | Give the shot. Call the clinic immediately — even if it is 2 AM. They will decide whether to adjust retrieval time

**More than 3 hours late** | Risk increases of immature eggs (if too early) or premature ovulation (if retrieval cannot be rescheduled) | Call the clinic before giving the shot. They will advise — they may adjust retrieval time or potentially cancel if ovulation has likely occurred

**Forgot entirely (discovered next morning)** | The cycle may still be salvageable depending on when you realise | Call the clinic as soon as you realise. Do NOT give the shot without speaking to the doctor. Retrieval may need significant rescheduling or cancellation

The bottom line: If you are late, call your clinic immediately. Most clinics have an after-hours number for exactly this situation. Do not wait until business hours. Call at 2 AM if you have to.

Side Effects of the Trigger Shot

Normal Side Effects (Not a Cause for Concern)

  • Mild bloating and abdominal discomfort — Your follicles are at their largest. This is normal.
  • Breast tenderness — hCG causes this. It peaks 2-3 days after the shot.
  • Injection site soreness — Standard for any injection.
  • Mood changes — The hormonal shift can cause irritability, tearfulness, or anxiety.
  • Mild headache — Common in the first 24 hours.

Warning Signs (Call Your Clinic)

  • Severe abdominal pain or bloating — Could indicate early OHSS
  • Nausea and vomiting — Early OHSS symptom
  • Difficulty breathing — Severe OHSS symptom — seek emergency care
  • Significant weight gain (>1 kg in 24 hours) — Fluid retention from OHSS
  • Signs of premature ovulation — Sharp, sudden pelvic pain followed by relief. This is rare but means the eggs may have released before retrieval.

Trigger Shot and Pregnancy Tests: Important Warning

hCG-based trigger shots (Ovidrel, Pregnyl) will cause a false positive pregnancy test for 7-14 days after injection. The trigger shot IS hCG — the same hormone that pregnancy tests detect.

If you take a home pregnancy test within 10-14 days of the trigger shot, a positive result means nothing. It is the trigger shot, not a pregnancy.

When to test reliably: Your clinic will schedule a blood beta-hCG test approximately 10-14 days after embryo transfer (not after the trigger). Follow their timeline, not a home test.

After the Trigger: What to Expect Before Retrieval

Timeframe | What Happens

**Night of trigger** | Give the shot at the prescribed time. Go to sleep.

**Next day (day before retrieval)** | You may feel bloated and full. This is normal. Stay hydrated. Eat a light dinner.

**Night before retrieval** | Nothing to eat or drink after midnight (fasting for anaesthesia). Your clinic will confirm the specific fasting time.

**Morning of retrieval** | Arrive at the clinic at the scheduled time. You will be prepped for the procedure (usually under IV sedation or light anaesthesia).

Do not take any other medications on trigger night or the morning of retrieval unless specifically instructed by your doctor. This includes stopping the daily gonadotropin injections (your last stimulation injection is usually the night before the trigger).

Questions to Ask Your Doctor

  1. 1"What is the exact time I should take the trigger shot?"
  2. 2"Which trigger medication are you prescribing, and why?"
  3. 3"Am I at risk for OHSS? Are you using a GnRH agonist trigger to reduce my risk?"
  4. 4"What is the after-hours number I should call if I have problems with the trigger?"
  5. 5"What time should I arrive for egg retrieval, and when should I stop eating and drinking?"
  6. 6"If I am even 30 minutes late with the trigger, should I call you?"

A Quick Checklist for Trigger Night

Print this or save it on your phone:

  • [ ] Medication name and dose confirmed with clinic
  • [ ] Medication taken out of fridge 15-20 minutes before injection time
  • [ ] All supplies ready (syringe, alcohol swab, cotton ball)
  • [ ] Alarm 1 set (30 minutes before)
  • [ ] Alarm 2 set (exact time)
  • [ ] Alarm 3 set (partner's phone)
  • [ ] Clinic's after-hours number saved in your phone
  • [ ] Injection given at _______ PM (write the time)
  • [ ] Confirm fasting time for retrieval: nothing after _______ PM/AM

Medical Disclaimer: This article is for informational purposes only and does not replace the specific medical instructions given by your fertility specialist. Trigger shot timing, dosage, and type must be determined by your prescribing doctor based on your individual cycle response. If you experience any concerning symptoms or miss your trigger shot, contact your clinic immediately. Never adjust medication timing or dosage without consulting your doctor.