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Blastocyst Culture – What It Means and Why It Matters in IVF

Dr. Pujil Gulati, IVF Specialist with over 13 years of experience in Assisted Reproductive Techniques BabyBloom IVF Gurgaon

May 2, 2025

🌱 What is Blastocyst Culture in IVF?

Blastocyst culture is a special step in the IVF (In Vitro Fertilization) process. In this step, the embryo is grown in the lab for 5 to 6 days instead of 3 days. This helps the embryo become stronger and healthier before placing it inside the woman’s womb (uterus).

🧫 What is a Blastocyst?

A blastocyst is a stage of embryo. It is formed on Day 5 or 6 after fertilization. At this stage:

The embryo has 100–120 cells
It has two main parts: inner cell mass (will become baby) and outer layer (will become placenta)
It is ready for implantation in the uterus

🧪 Doctors believe blastocyst is more developed and gives better IVF success.

🗓️ Stages of Blastocyst Culture in IVF

Let’s understand it step-by-step:

✅ Step 1: Egg Collection

Mature eggs are taken from the woman’s ovaries.

✅ Step 2: Sperm Collection

Sperms are taken from the male partner (or donor).

✅ Step 3: Fertilization (Day 0)

Egg and sperm are mixed in the lab using IVF or ICSI method.

✅ Step 4: Embryo Development

The fertilized egg becomes a 2-cell, 4-cell, 8-cell embryo over 3 days.

✅ Step 5: Blastocyst Formation (Day 5-6)

Some embryos grow into blastocysts on Day 5 or 6.

✅ Step 6: Embryo Transfer

One or two healthy blastocysts are transferred into the woman’s uterus.

🧠 Why is Blastocyst Culture Important in IVF?

1. 👶 Higher Success Rate

Blastocyst is more developed, so it implants better in the uterus. This increases the chance of pregnancy.

2. 🧬 Better Embryo Selection

Doctors can see which embryo is growing well and choose the best one for transfer.

3. 🧪 Lower Risk of Multiple Pregnancies

Only one good-quality blastocyst is usually enough, so no need to transfer 2-3 embryos.

4. ❄️ Better for Freezing (Cryopreservation)

Blastocysts can be frozen safely for future use.

📊 Success Rate of Blastocyst Transfer in IVF

Success rate with Day 3 embryos = 30–35%
Success rate with blastocyst (Day 5) = 50–60% or more (varies by age and clinic)

👩‍🍼 For women under 35, the success is even higher with blastocyst transfer.

🧬 Who Should Choose Blastocyst Culture?

Women with multiple embryos on Day 3
Couples with previous IVF failure
Women under 35 with good egg quality
Patients choosing PGT (Preimplantation Genetic Testing)

❓ Is Blastocyst Culture Risky?

Mostly it is safe. But in some cases:

Not all embryos reach blastocyst stage
Some couples may not have any embryo left for transfer

That’s why this method is not for everyone. Your IVF doctor will guide you best.

🔬 Fresh vs Frozen Blastocyst Transfer

Both are successful. But in many cases, frozen blastocyst transfer gives better results because:

The woman’s body gets more rest after egg retrieval
The uterus lining becomes more natural
Hormone levels are more stable

📋 Summary Table

Topic	Details
What is Blastocyst Culture	Growing embryo till Day 5 or 6 in lab
Best Stage for Transfer	Blastocyst (100+ cells, ready to implant)
IVF Success Rate	Up to 60% with blastocyst
Who Should Choose It	Couples with good embryos or past failure
Risks	Not all embryos may survive till Day 5
Fresh vs Frozen Transfer	Frozen often gives better results

❓ FAQs About Blastocyst Culture in IVF

Q1: Is blastocyst transfer better than Day 3 embryo transfer?

Yes, it gives a higher chance of pregnancy as the embryo is more mature.

Q2: How many days after IVF is blastocyst transfer done?

Usually on Day 5 or Day 6.

Q3: Can all embryos grow into blastocysts?

No, only the best embryos grow to blastocyst stage.

Q4: Is the blastocyst transfer painful?

No, it’s a simple, painless procedure like a pap smear.

Q5: Is success guaranteed with blastocyst?

No IVF method gives 100% success, but blastocyst increases chances

🌟 Conclusion

Blastocyst culture in IVF is a powerful technique that increases the chances of successful pregnancy. It allows fertility doctors to choose the healthiest embryos for transfer, leading to higher IVF success rates and a better chance at parenthood. ❤️ OR If you need any information related to IVF, contact our Babybloom IVF Centre or call us at 9266046700 to clear your doubt🌸