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What Happens If My IVF Cycle Gets Cancelled?
For eight to fourteen days you have been giving yourself injections on a fairly forgiving schedule. Within an hour or two of your usual time is fine. Then your clinic calls with your trigger instructions and gives you a time like 9:45 PM, and suddenly the flexibility is gone entirely.
The trigger shot is the single most time-sensitive injection in your entire cycle. It is also usually the last one before retrieval, which means most patients are giving it while exhausted, anxious, and running on very little sleep. That combination is exactly why it is worth understanding it fully before trigger night arrives.
This guide covers what the trigger shot actually does, the differences between the medication types your clinic might prescribe, what happens hour by hour, and what to do if something goes wrong.
"Every other injection in your cycle has a window. The trigger shot has a moment."
The short version
Trigger shot, by the numbers
1
injection, given once
At an exact time
34–36
hours until your retrieval
Scheduled by your clinic
38–40
hours until natural ovulation
The window you are beating
That gap between 36 hours and 40 hours is the entire reason timing matters so much. Your retrieval is deliberately scheduled just before your body would release the eggs on its own. Too late, and the follicles may have already emptied.
What it does
Why a single injection changes everything
Throughout stimulation, your follicles have been growing but the eggs inside them are not finished maturing. In a natural cycle, a surge of luteinizing hormone (LH) from your pituitary gland completes that final maturation step and releases the egg. During IVF, the medications suppressing premature ovulation, Cetrotide or Ganirelix, have deliberately blocked that surge from happening.
The trigger shot replaces it. It delivers the signal your body has been prevented from sending, telling every mature follicle to finish the job at the same time. Roughly 36 hours later your retrieval collects them, just before they would release naturally.
This is why your RE waits until your lead follicles reach 18 to 20mm before triggering, and why your estradiol pattern matters in that final decision. Trigger too early and the eggs are immature. Trigger too late and you risk losing follicles to spontaneous ovulation.
Medication types
hCG, Lupron, or both
Your protocol will specify one of three approaches. Which one you get depends primarily on your OHSS risk and whether you are doing a fresh or frozen transfer.
| Trigger type | How it works | Typically used when |
|---|---|---|
| hCG (Ovidrel, Pregnyl, Novarel) | hCG is structurally similar to LH and acts directly on the follicles to complete maturation. | Standard protocols, average responders, fresh transfer planned. |
| Lupron (leuprolide) | Prompts your own pituitary to release a natural LH and FSH surge rather than mimicking it. | High responders, elevated OHSS risk, freeze-all cycles. |
| Dual trigger | Both medications given, sometimes hours apart, to combine the benefits of each. | Patients with a history of poor egg maturity or mixed risk profiles. |
The Lupron trigger significantly reduces OHSS risk, which is why it has become the preferred approach for high responders. It does require a freeze-all cycle in most cases, since the shortened luteal support it produces is not ideal for a fresh transfer. If your clinic switches you to a Lupron trigger late in stimulation, this is usually why.
Delivery method varies too. Ovidrel comes as a prefilled subcutaneous autoinjector and is the simplest to administer. Pregnyl and Novarel come as a powder requiring reconstitution and are often given intramuscularly. Our Injecting 101 guide covers technique for each.
Trigger night
Hour by hour, what actually happens
Day
of
of
Morning monitoring
Your clinic confirms you are ready and gives you a time
Your final monitoring appointment confirms lead follicles at 18 to 20mm and an estradiol level consistent with that follicle count. Your clinic then calls with two pieces of information: your exact trigger time and your retrieval time. Write both down. Ask them to repeat the trigger time back to you. This is not a moment to rely on memory.
2 hrs
before
before
Preparation
Get the medication and supplies out early
Take the medication out of the refrigerator if it is stored cold and let it reach room temperature. Lay out your alcohol swabs, needles, and sharps container. If your trigger requires mixing, read the instructions now rather than at the moment you need to inject. Set two alarms, one for 30 minutes before and one for the exact time.
Trigger
time
time
The injection
Give the shot at the time you were given
Within a few minutes of the stated time is fine. Subcutaneous triggers go into the abdomen or upper thigh; intramuscular triggers go into the upper outer quadrant of the buttock. If you have a dual trigger, your clinic will specify whether the two injections are simultaneous or spaced. Confirm you have injected the full dose.
0–12
hrs
hrs
Overnight
Final maturation begins
Inside each mature follicle, the egg completes the final stage of maturation. You will likely feel nothing new beyond the bloating and pelvic pressure already present from stimulation. Some patients notice a slight increase in fullness. Sleep is often difficult on trigger night, which is normal and not a problem.
34–36
hrs
hrs
Retrieval
Egg retrieval under sedation
The procedure takes 20 to 30 minutes. You will be under sedation and will not feel it. Nothing to eat or drink after midnight, and you will need someone to drive you home. You will know the number of eggs retrieved the same day; fertilization results come the following morning. Read our full IVF timeline for what follows.
No stimulation medications on trigger night
Unless your clinic explicitly tells you otherwise, you stop your FSH injections and your antagonist (Cetrotide or Ganirelix) once the trigger is given. Many patients are unsure about this and either double up or skip something they needed. If your instructions are not completely clear, call your clinic before trigger time, not after.
If something goes wrong
Troubleshooting trigger night
Things do go wrong, and most of them are fixable. Here is what to do.
I missed the exact time
Under 30 minutes is usually low impact
If you are within about 30 minutes of your scheduled time, give the injection now and notify your clinic. Delays in that range typically have minimal impact. If more time has passed, call your clinic's after-hours line immediately before injecting. They may adjust your retrieval time to compensate. Do not guess and do not skip it.
What you should never do is give a second dose to make up for a late one. A double dose does not correct timing and introduces its own risks.
The autoinjector failed or I am not sure I got the full dose
Call immediately, do not re-dose on your own
If the pen jammed, the needle came out early, or you saw significant liquid on your skin, call your clinic's after-hours line right away. They will decide whether a partial dose is sufficient or whether you need additional medication. If additional medication is needed urgently, call Prima at (718) 230-3535. We are available 24/7 and can arrange emergency delivery in the New York City area.
A small drop of liquid at the injection site after withdrawing the needle is normal and does not mean the dose was lost.
My trigger medication has not arrived yet
The most preventable problem on this list
Your trigger should be in your hands days before you need it, not the afternoon of. When your protocol is written, confirm your trigger medication is included in your first shipment rather than sent separately. If it is not in your possession by the time you enter late stimulation, call Prima immediately at (718) 230-3535 so we can get it to you before your monitoring appointment, not after.
Prima offers same-day delivery in New York City and next-day nationwide, Monday through Saturday. But the safest position is having the medication in your refrigerator before you need it.
What side effects should I expect after triggering?
Mostly a continuation of what you already feel
Most patients notice bloating and pelvic fullness that may intensify slightly, mild injection site soreness, and occasionally a headache or fatigue. These are consistent with what you have already been experiencing during stimulation. hCG triggers carry a higher OHSS risk than Lupron triggers, and OHSS symptoms typically peak 3 to 5 days after trigger.
Call your clinic immediately for rapid weight gain of more than two pounds overnight, severe abdominal pain, shortness of breath, or inability to urinate. Our stimulation guide has a full symptom reference covering what is normal and what needs attention.
Can I take a pregnancy test after an hCG trigger?
It will be positive, and it will not mean anything
An hCG trigger puts hCG directly into your bloodstream, which is exactly what a home pregnancy test detects. Testing in the days after triggering will produce a positive result that reflects the medication, not a pregnancy. It typically takes 10 to 14 days for trigger hCG to clear. This is one of the most common sources of false hope in IVF, and it is why your clinic uses a blood beta-hCG at a specific point rather than home tests.
A Lupron trigger does not contain hCG and will not cause this effect.
Where Prima fits in
The one medication you cannot be waiting on
Every medication in your cycle matters, but the trigger is the only one where a delivery delay can end the cycle. There is no rescheduling around it and no substituting something else you have on hand.
Prima ships your trigger with your protocol rather than separately, so it is in your refrigerator well before your clinic gives you a time. If your protocol changes mid-cycle and your trigger type switches from hCG to Lupron, your clinic notifies us directly and we ship the replacement. And if something goes wrong on trigger night itself, we answer the phone. Call or text (718) 230-3535 any time.
IVF stimulation, day by day
Everything leading up to trigger
Injecting 101
Subcutaneous and intramuscular technique
Medications 101
Every fertility drug explained
The full IVF timeline
What happens after retrieval
All fertility medications
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The trigger shot is a single injection at the end of a long, difficult stretch. Read your instructions twice, set two alarms, and have the medication in hand days ahead. That is genuinely most of it.
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Clinical Note
Timing windows and medication descriptions in this post reflect current clinical practice as described by Fertility Centers of New England (May 2026), Coastal Fertility and CFMC (May 2026), Liv Hospital (Apr 2026), and Indiana Fertility Institute. Individual protocols vary and your clinic's specific instructions always take precedence over general guidance. This content is educational and does not constitute medical advice. Always follow the exact trigger time your clinic provides and contact your care team with any questions.
