Embryo Arrest at Day 3 vs. Day 5: Why It Happens and What to Do Next

Receiving the news that your embryos have stopped growing (arrested) is one of the most devastating moments in a fertility journey. You’ve done the stims, the retrieval, and the waiting, only to be told that the journey has ended before transfer.

If you have been diagnosed with Low AMH or Diminished Ovarian Reserve (DOR), your clinic might be quick to blame "old eggs" and suggest donor eggs as your only path forward.

But before you accept that as your final answer, you need to understand the science of why embryos arrest and how the 90-day maturation window can change your next outcome.

Day 3 vs. Day 5: Who is Responsible?

In the embryology lab, the timing of when an embryo stops growing provides a massive clue into what is happening at the cellular level.

• Arrest Before Day 3: This is almost always related to egg quality. The egg provides the "machinery" (mitochondria) for the first few days of division. If the egg lacks the cellular energy to fuel these divisions, the embryo stalls.

• Arrest Between Day 3 and Day 5: This is the "Genomic Activation" phase. This is when the embryo’s own DNA and the paternal (sperm) contribution take over. If an embryo makes it to Day 3 but fails to reach Day 5 (Blastocyst), we have to look at DNA fragmentation, oxidative stress, and the internal environment of both partners.

The "90-Day Window" Opportunity

Most conventional clinics treat embryo arrest as a stroke of bad luck or an inevitable sign of age. In functional fertility, we see it as a sign of a compromised environment.

It takes approximately 90 days for an egg to mature before it is ovulated or retrieved. During these three months, the egg is highly sensitive to:

1. Mitochondrial Health: The "batteries" that drive embryo division.

2. Systemic Inflammation: Which can damage the delicate DNA of the egg.

3. Nutrient Density: Ensuring the egg has the raw materials to survive the lab environment.

Why "More Drugs" Isn't the Answer

If you have Low AMH, a common clinical response is to "max out" your stimulation meds. However, for many women, high doses of hormones in a high-inflammation environment lead to lower egg quality.

Instead of rushing into another cycle to get the "same" results, you need to spend the next 90 days "priming the soil."

Stop Guessing. Start Investigating.If your embryos are arresting and you’ve been told your "numbers" are the problem, you need a Functional Second Opinion. We look at the underlying imbalances, from gut health to oxidative stress, that your clinic isn't testing for.

Read our Full Low AMH & Functional Second Opinion Guide

What to Ask Your Doctor at Your Next Follow-Up

If you’ve experienced embryo arrest, don't just ask "What happened?" Ask these three questions:

1. "At what exact hour or day did the arrest occur?"

2. "What was the fragmentation grade on Day 3?"

3. "Based on the arrest timing, are we looking at an oocyte (egg) energy issue or a DNA fragmentation issue?"

Your Next Step

Embryo arrest is a message from your body, not a final verdict. By focusing on your functional health today, you are impacting the quality of the eggs you will retrieve 90 days from now.

Ready to change your strategy? Book Your Functional Second Opinion today.

Frequently Asked Questions (FAQ)

Q: Does Day 3 arrest always mean I need donor eggs? A: Absolutely not. While clinics often jump to donor eggs as a "quick fix" for egg quality issues, Day 3 arrest is often a sign of poor mitochondrial energy. Since it takes 90 days for an egg to mature, we can significantly improve that cellular energy (ATP) through targeted nutrition, antioxidant support, and inflammation reduction before your next retrieval.

Q: Can sperm quality cause embryos to stop growing after Day 3? A: Yes. This is a common "missing piece" in fertility treatments. Around Day 3, the embryo's own genome activates, which includes the paternal DNA. If there is high sperm DNA fragmentation or oxidative stress, the embryo may fail to reach the blastocyst stage (Day 5), even if the eggs are healthy.

Q: Why did my "good grade" Day 3 embryo not make it to Day 5? A: Grading is based on appearance, not internal health. A "Grade A" embryo can still have chromosomal abnormalities or insufficient mitochondrial "fuel" to survive the transition to the blastocyst stage. This is why we focus on the environment the egg grew in for the three months prior.

Q: Should I do a Day 3 transfer instead of waiting for Day 5? A: Some clinics suggest this to "get the embryo back in the body," but if the embryo is arresting due to DNA issues or lack of energy, the location (uterus vs. lab) won't always change the outcome. The better strategy is to spend 90 days improving egg and sperm quality, so the embryos have the strength to reach Day 5.