The prequel most people never hear
You prepped for retrieval like it was a marathon.
You took the supplements.
You did the injections.
You pushed through because the calendar said it was time.
Then on Day 3 or Day 4, the embryos just stopped.
Most people are told:
It is bad luck.
It is egg quality.
Sometimes embryos arrest.
What is usually missing is the chapter that explains why embryos can stop growing even when the DNA itself is normal.
This is that chapter.
If you are specifically trying to understand why embryos often stop growing around Day 3, read The Day 3 Cliff: Why Your Embryos Stopped Growing
If you are new here, start with our main fertility foundation article.
First, an important clarification
This is not about blame.
It is not about effort.
It is not about doing something wrong.
It is about whether the biological system had enough stored energy to meet an extreme demand.
Good instructions are not enough if there is no power to run them.
The science behind the egg fizzle
An egg is a unique cell.
It is the only cell in the human body that must survive for several days using stored energy alone.
For the first few days after fertilization, the embryo does not produce its own energy. It relies entirely on the mitochondria passed down from the egg.
These mitochondria power every cell division from Day 1 through Day 3.
If the system does not have enough reserve, development can slow or stop before the embryo reaches the next stage.
This is what many people experience as an unexplained arrest.
Not because the blueprint was defective, but because the power source could not sustain the workload.
This becomes clearer when you understand how Day 3 and Day 5 embryos develop.
Why the battery drains before retrieval
There are a few common reasons eggs enter a cycle with a limited reserve.
Blood sugar instability
Frequent spikes and crashes place heavy demand on mitochondria.
Skipping meals, under eating, overtraining, or running on caffeine and adrenaline drains energy long before retrieval begins.
Mineral depletion
Mitochondria cannot hold a charge without the right materials.
Low magnesium, inadequate CoQ10 availability, and micronutrient gaps reduce how much energy an egg can store.
A rushed cycle
Many people begin retrieval already exhausted.
High functioning, wired, pushing through, planning to rest later.
Retrieval is one of the most energy intensive events in human biology.
Asking a depleted system to perform at peak output is a mismatch, not a failure.
A necessary boundary
No protocol recharges an egg during an active cycle.
Nothing in this article suggests stopping a cycle.
Nothing here explains the outcome of any single retrieval.
This explains why preparation and pacing matter before the cycle begins.
When a second set of eyes matters
If you are unsure how this applies to your specific cycle, labs, or embryo history, this is where a Functional Fertility Second Opinion can help.
This is not a new protocol and not a rush decision.
It is a structured review of what has already been done, what may have been missed, and whether timing or physiology could be influencing outcomes.
The perspective shift
Success is not about producing more eggs.
It is about producing eggs with enough stored energy to complete early development.
This is why a three month preparation window is not wasted time.
It is a charging period.
The goal is not to do more.
It is to stabilize blood sugar, restore minerals, and allow the system to rebuild reserve before asking it to perform again.
If this resonates
If you are reading this and thinking, “I rushed,” do not try to fix everything at once.
Start with one question:
Is my blood sugar stable day to day?
That single factor influences mitochondrial output, mineral retention, and stress signaling more than most people realize.
If you want clarity before your next step
Many people seek a Functional Fertility Second Opinion when they are deciding whether to proceed, pause, or change course.
It is designed to answer one question clearly:
Is my body resourced enough to support early embryo development right now?
This can be especially helpful after an unexpected Day 3 or Day 5 arrest, or before committing to another retrieval.
Many people arrive at this point after what feels like a WTF appointment.
You met with your REI.
You reviewed the cycle.
You were told the embryos stopped growing.
And when you asked why, the answer was some version of “sometimes this just happens.”
If that explanation felt empty or dismissive, you are not alone.
I wrote more about this exact moment here:
The WTF Appointment: IVF Failure, Embryo Arrest, and When Nothing Makes Sense
About Sarah Clark & Fab Fertile
Sarah Clark is the founder of Fab Fertile and host of Get Pregnant Naturally. Her work focuses on identifying overlooked biological patterns in couples facing failed IVF, low AMH, embryo arrest, diminished ovarian reserve, premature ovarian insufficiency, and recurrent pregnancy loss.
For over a decade, Sarah and the Fab Fertile team have reviewed hundreds of complex fertility cases, helping couples understand why outcomes stalled when standard testing appeared normal. Their approach emphasizes pattern recognition across both partners, functional testing, and informed collaboration with medical providers.
Fab Fertile provides education and lifestyle-based support alongside medical care. It does not replace diagnosis or treatment by a licensed physician.
