When navigating the world of IVF, choosing the right protocol is one of the most important decisions for you and your outcome.
The mission is simple yet delicate: stimulate your ovaries to produce multiple mature eggs while also minimising risks and emotional and financial strain.
We have experienced a wide variety of ovarian stimulation protocols in our IVF journeys but knew little about the protocols initially. In this blog, we’ll break down four of the most commonly used IVF stimulation protocols and three more emerging ones.
We’ll explain how each works, who it’s best suited for, and what you can expect— to help demystify the process and make you feel more informed and empowered on your fertility journey.
How Doctors Choose the Right IVF Protocol
Choosing the right ovarian stimulation protocols in IVF is one of the most important steps in your fertility journey. Your doctor will tailor the approach based on your age, BMI, ovarian reserve, hormone levels, and past IVF responses.
You can expect the following assessments:
AMH (Anti-Mullerian Hormone): Measures your remaining egg supply.
AFC (Antral Follicle Count): An ultrasound that counts small follicles in the ovaries.
Clomiphene Challenge Test: Assesses ovarian reserve by checking hormone response before and after Clomid.
FSH & Estrogen (E2) Levels: Help estimate egg quality and stimulation potential.
If you’ve had IVF treatments already, doctors will also consider:
Number of eggs previously retrieved
Dosage of medications used
Whether cycles were canceled
Response quality and embryo development
What type of Responder are you?
As an IVF Patient you will usually fall into one of three categories based on how well you respond to the stimulation. Each responder type presents its unique challenges to the doctor.
High Responders (15+ eggs)
- Often younger or diagnosed with PCOS
- More eggs but also at a higher risk of Ovarian Hyperstimulation Syndrome (OHSS)
- Benefit from mild or tailored protocols to reduce complications
The good news is that high responders tend to collect more eggs and have higher success rates, but they are also at a greater risk for OHSS if not carefully monitored. By recognising high responders early the doctor can opt for a milder, safer stimulation protocols to reduce complications.
Intermediate Responders (6-14 eggs)
- Most common category
- Responses vary cycle-to-cycle, requiring close monitoring and medication adjustments
While this may sound ideal, it can be challenging to manage because their response can be unpredictable and sensitive to medication adjustments. Finding the right balance in stimulation is crucial, as a slight change can lead to under- or over-response.
Poor Responders (1-5 eggs)
- Common in women over 35 or those with low ovarian reserve
- Requires gentle and innovative protocols to improve egg quality and yield
A poor ovarian response happens in about 9–24% of IVF cycles often resulting in lower chances of fertilization, embryo development, and pregnancy. Research indicates that low responders require more gentle and innovative methods of stimulation.
Now let’s get on to the protocols.
Mainstream IVF Stimulation Protocols
GnRH Agonist Long IVF Protocol – The Traditional Gold Standard
Who it’s best for
- If you have a regular cycles and good ovarian reserve
How it works
- Hormone Suppression: Begin suppression with a medication like triptorelin, leuprorelin, deslorelin, goserelin and nafarelin around day 21 to reset hormone levels.
- Ovarian Stimulation: After 10–14 days, start daily FSH/LH injections.
- Trigger & Retrieval: When follicles reach 16–18 mm, an injection triggers final maturation, and eggs are retrieved 34–36 hours later.
Pros
- Produces a higher number of mature follicles and embryos.
- Well-studied and reliable
Cons
- Longer timeline
- Higher medication load
- Risk of OHSS
The GnRH agonist long protocol has been a trusted IVF protocol since its discovery in the 1980s and is often considered the “gold standard” for many clinics. Your natural cycle will be completely suppressed to create a controlled environment and give your doctor full control.
This protocol offers a high level of control and typically leads to a good number of mature eggs, making it a reliable choice—especially if you have regular cycles and good ovarian reserve.
GnRH Antagonist Protocol – A Shorter, Flexible Option
Who it’s best for
- If you are at risk for OHSS (like PCOS)
- If you prefer a shorter treatment
How it works
- Stimulation Starts Early: Begin gonadotropins on day 2 or 3.
- Add Antagonist: Start antagonist medication like cetrorelix, abarelix, cetrorelix, degarelix or ganirelix) when follicles reach ~14 mm.
- Trigger & Retrieval: Use an injection to mature eggs; retrieve after 34–36 hours.
Pros
- Shorter treatment duration and fewer injections
- Lower OHSS risk
Cons
- Slightly lower pregnancy rates in some cases
- Fewer eggs retrieved than with the agonist protocol
The GnRH antagonist protocol is a more modern and flexible approach to IVF stimulation, often chosen for if you are at risk of ovarian hyperstimulation syndrome (OHSS) or prefer a shorter treatment timeline. As your natural hormones aren’t as suppressed as in the GnRH agonist long protocol, the treatment period is typically shorter, about 2-3 weeks.
Throughout the process, your progress will closely monitored with ultrasounds and hormone blood tests to track estrogen, LH, FSH, and progesterone levels. If your hormone levels rise too quickly, especially LH and estrogen, extra care is taken to avoid premature ovulation or complications like OHSS.
This protocol is popular for its simplicity and lower risk profile, especially in women with PCOS or those who’ve had previous complications with IVF stimulation.
Short GnRH Agonist/ Lupron Flare Protocol – A Boost for Poor Responders
Who it’s best for
- If you have a history of poor ovarian response
How it works
- Agonist/Lupron Flare: Begin low-dose Lupron on day 2 or 3 to cause a hormone surge/ flare.
- Add Gonadotropins: Support ovarian stimulation with FSH injections.
- Trigger & Retrieval: Monitor closely, then trigger and retrieve eggs.
Pros
- Can improve response in difficult cases
Cons
- Not ideal if you are at risk of overstimulation
The Short Lupron Flare Protocol is a specialised IVF approach often recommended if you have had a poor response to standard stimulation in the past. It’s designed to give your ovaries a quick hormonal “kick-start” before transitioning into controlled stimulation.
This protocol is especially useful if you have diminished ovarian reserve or are age 35 or above, where a stronger initial response can make a significant difference.
Minimal Stimulation Protocol – A Gentler, Cost-Effective Option
Who it’s best for
- If you are over 38 or with low ovarian reserve
- If you want a natural, lower-cost approach
How it works
- Oral Medication: Begin Clomid or Letrozole early in the cycle.
- Add Low-Dose Gonadotropins: Stimulate a few high-quality eggs.
- Trigger & Retrieval: Monitor and retrieve eggs once mature.
Pros
- Lower medication costs
- Reduced OHSS risk
Cons
- Fewer eggs and embryos
- Not ideal for those needing embryo freezing
Also known as “Mini IVF” or Mild Stimulation, the Minimal Stimulation Protocol uses lower doses of medication to gently encourage the ovaries to produce eggs. It’s a good option if you want to try a more natural approach if you have a low ovarian reserve.
This protocol is less intense, more affordable, and carries a very low risk of OHSS. While fewer eggs are typically retrieved, they may be of higher quality, which is especially valuable if you are over 38 or haven’t responded well to high-dose protocols.
Specialised & Emerging IVF Protocols
In addition to the four main IVF protocols, there are several other less common protocols that you may want to keep an eye on and ask your clinic about.
Natural Cycle IVF – Minimal Medication, Maximum Simplicity
Who it’s best for
- If you ovulate regularly
- If you want to avoid fertility drugs
- If you have a very low ovarian reserves
How it works
- Follow natural ovulation.
- Monitor hormone levels.
- Retrieve the naturally selected egg.
Pros
- No stimulation drugs
- Zero OHSS risk
Cons
- One egg per cycle
- Higher chance of cancellation
Natural Cycle IVF is the most medication-free approach to IVF. Instead of stimulating the ovaries to produce multiple eggs, this protocol follows your natural menstrual cycle and retrieves the single egg that your body releases that month.
Duo-Stimulation IVF – Two Cycles in One
Who it’s best for
- If you have a low ovarian reserve
- If you’d like to maximise the number of eggs retrieved
How it works
- Stimulate during the follicular phase.
- Retrieve eggs.
- Stimulate again during the luteal phase and retrieve more eggs.
Pros
- Can double the number of eggs retrieved in one monthMore intense
- Efficient for patients with limited time or low egg yield
Cons
- More complex and intense
- Not available at all clinics
Also called “Dual Stim” or “Double Stimulation”, Duo-Stimulation IVF involves stimulating the ovaries twice in the same menstrual cycle—once during the follicular phase and again during the luteal phase. It’s particularly useful if you’d like to maximize egg retrieval in a short time for example before cancer treatment, if you have trouble creating blastocysts (as you’ll have more eggs), or for egg freezing.
Microdose Flare IVF – Gentle but strategic
Who it’s best for
- If you have a poor ovarian response
- If you haven’t done well on standard protocols
How it works
- Start very low-dose suppression early in the cycle.
- Add gonadotropins to stimulate follicles.
- Trigger and retrieve eggs after close monitoring.
Pros
- Gentle stimulation with focused results
- A good option if you have diminished ovarian reserve
Cons
- Requires precise timing and monitoring
- May be less effective in severe cases of ovarian dysfunction
This protocol is a variation of the Short GnRH Agonist/ Lupron Flare Protocol using very small doses of a GnRH agonist (like Lupron) to create a brief surge—or “flare”—of FSH and LH to stimulate the ovaries
Choosing the Right Stimulation Protocol: What Matters Most
When it comes to IVF, there’s no one-size-fits-all solution. The best protocol for you depends on a combination of your unique biology and your treatment history. It’s completely normal to find that different doctors or clinics may suggest new strategies or tweak protocols based on how your body responded in previous cycles. We have tried this many times and it’s usually a good sign. At times, it can feel like trial and error—but that’s often part of finding what works best for you
We’ve deep dived into all the factors that determine which protocol is the right one for you. Here’s how that often plays out:
- If you are a high responder (ie. you have PCOS) you’ll usually do better with antagonist protocols, which reduce the risk of overstimulation.
- If you are a poor responder or over 38 years old you may benefit from minimal stimulation protocols, which are gentler and more cost-effective.
- If you are a normal responders you’ll probably try the long GnRH agonist protocol first, which offers a controlled and predictable stimulation process.
Final Thoughts
We believe that understanding the different IVF protocols is about feeling informed, confident, and empowered in understanding the choices made about your body and why. Whether you’re a high, intermediate or poor responder, your response to treatment is deeply personal, and your protocol should reflect that.
Each IVF protocol has its strengths and trade-offs and it’s not uncommon to try more than one strategy over time. What may feel like trial and error is often how progress is made in the world of IVF. If the main four protocols are not achieving good results then don’t be afraid to look further to the more specialised and emerging protocols.
At the heart of it all is your clinic and doctor taking time to understand your body. And by working closely with your fertility team—sharing your history, asking questions, and staying involved—you help shape a protocol that supports your body and your goals.
If you’re just beginning or considering a new cycle, take this guide as a tool for discussion with your doctor. You’re not just a patient; you’re a key partner in this process.
Your body. Your journey. Your protocol. And with the right information, you’re already one step closer.
Research and Evidence Behind IVF Stimulation Protocols
The information in this blog is supported by peer-reviewed studies and scientific research. If you’d like to learn more or explore the details, feel free to check out the sources below.
1. Lewis, C. (2018, August 28). No benefit to frozen embryo transfer for IVF in low and intermediate responders. Duke Health. Retrieved from https://physicians.dukehealth.org/articles/no-benefit-frozen-embryo-transfer-ivf-low-and-intermediate-responders
2. Bosch, E., Labarta, E., Crespo, J., Simón, C., Remohí, J., Jenkins, J., & Pellicer, A. (2001). A prospective randomized study comparing the effect of follicle-stimulating hormone and human menopausal gonadotropin on follicular development and oocyte quality. Fertility and Sterility, 76(1), 77–82. Retrieved from https://www.sciencedirect.com/science/article/pii/S001502820102893X
3. Roque, M., Lattes, K., Serra, S., Sola, I., Geber, S., Carreras, R., & Checa, M. A. (2015). Fresh embryo transfer versus frozen embryo transfer in in vitro fertilization cycles: A systematic review and meta-analysis. JBRA Assisted Reproduction, 19(1), 18–25. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4486909/
