Fertilized Egg to Blastocyst Success Rates: The Numbers You Need to Know

Fertilized Egg to Blastocyst Success Rates: The Numbers You Need to Know

If you’re going through IVF, one of the most important stages in the process is getting embryos to the blastocyst stage. But how many fertilized eggs actually make it that far? Knowing the answer to "what percentage of fertilized eggs make it to blastocyst" helps set realistic expectations and gives insight into your chances for success.

In this guide, we break down the latest numbers, explain the factors that impact blastocyst development, and show what it all means for your IVF journey.

What Is a Blastocyst?

A blastocyst is an embryo that has developed for 5 to 6 days after fertilization. At this stage, the embryo has divided many times and consists of around 100–120 cells.

Why is the blastocyst stage important?

• It’s a critical milestone in embryo development.
• Embryos that reach this stage have a higher chance of successful implantation.
• Blastocyst culture allows the selection of the strongest embryos for transfer.

What Percentage of Fertilized Eggs Make It to Blastocyst?

This is the question most patients ask. The answer depends on many factors, but here are typical success rates:

General average: Across all ages, approximately 40% to 50% of fertilized eggs make it to the blastocyst stage.

Why Don’t All Fertilized Eggs Become Blastocysts?

There are several reasons why embryos may arrest before reaching blastocyst:

• Genetic abnormalities in the egg or sperm
• Chromosomal errors during cell division
• Poor egg quality (more common with age)
• Suboptimal sperm quality
• Laboratory conditions (culture medium, lab environment)
• Embryo grading (some embryos grow slower than others)

It’s normal for many fertilized eggs to stop developing before day 5–6—even in younger women.

Blastocyst Success Rates and Embryo Grading

Not all blastocysts are equal. They are graded based on:

• Expansion (size of the fluid cavity)
• Inner cell mass quality (which forms the baby)
• Trophectoderm quality (which forms the placenta)

The strongest (highest-grade) blastocysts have the best chance of implantation and live birth.

Typical outcomes:

• 1 high-grade blastocyst → 50%–70% chance of implantation (under 35)
• 2 good-quality blastocysts → even higher cumulative success

How Many Eggs Are Needed to Get a Blastocyst?

Since not all fertilized eggs make it to blastocyst, more eggs increase your odds. Here’s a rough guide:

How to Improve Blastocyst Rates

Though age is the main factor, you can help optimise your results:

• Choose an experienced IVF clinic with excellent lab conditions.
• Personalised stimulation protocols to boost egg quality.
• Pre-cycle lifestyle: Healthy BMI, stop smoking/alcohol, antioxidant supplements.
• Sperm health: Encourage your partner to optimise sperm quality.

Working with a specialist like Assoc. Prof. Dr. Nurettin Türktekin ensures every aspect of your cycle is optimised for success.

Emotional Impact: Preparing for Blastocyst Results

It’s normal to feel nervous while waiting to hear how many blastocysts have developed. Remember:

• Egg quantity is only part of the picture.
• One strong blastocyst can result in a healthy baby.
• Multiple cycles may be needed to bank enough embryos.

A compassionate IVF team will guide you through each step with realistic expectations.

Final Thoughts

Understanding what percentage of fertilized eggs make it to blastocyst helps you approach IVF with clarity and confidence. While the numbers may sound daunting, remember that each cycle brings valuable information, and every embryo counts.

If you’re considering IVF, Assoc. Prof. Dr. Nurettin Türktekin offers expert guidance, personalised care, and an outstanding track record in helping patients achieve high blastocyst success rates.

Ready to start your IVF journey? Contact Assoc. Dr. Nurettin Türktekin today for a consultation and tailored fertility plan.