Blastocyst Culture – Blastocyst Transfer

The biggest challenge in IVF success is to select the best embryo for transfer which will develop as a normal pregnancy. Most common reason for embryos not implanting is a genetic abnormality in the embryos.

There are very good monitoring parameters to judge which embryo is better. That includes egg quality, embryo development speed, embryo quality etc. However, better techniques are required.

Culturing the embryos in IVF lab till blastocyst stage – blastocyst culture, Preimplantation genetic testing – PGS– PGT – A, are the two best options. Blastocyst culture has many advantages over PGS. It is non-invasive on embryos, simpler to do, much less expensive also. The limitation is that it does not tell about the actual genetic constitution of the embryos.

Blastocyst and natural pregnancy

When an embryo becomes 5 to 6 days old, it reaches a stage of development which is called “ BLASTOCYST ”. In natural conception, the sperm fertilizes the egg in the fallopian tube. The embryo grows in the fallopian tube and slowly moves towards the uterus. An embryo reaches the uterus – endometrium after 4 to 6 days of fertilization at the blastocyst stage.

What is a Blastocyst?

All embryos which look good on day 2 or 3 of development may not develop further. If we culture them for more days, only the good quality embryos of them may develop further and reach the blastocyst stage successfully. The remaining stop developing at various stages in between. It is impossible to know which embryos will reach the blastocyst stage.

We can select and transfer one or two blastocysts and still achieve a very good pregnancy rate. This is called Blastocyst Culture.

Why Blastocyst culture?

  • Embryos selected by blastocyst culture have higher chances of implantation.

  • We know that only a few and not all of the transferred embryos can develop further and result in pregnancies. To compensate for this “stopped development” of a few embryos, we transfer more embryos at the 4 to 8 cell stage to achieve a better pregnancy rate.
    When we transfer more embryos, the chance of pregnancy increases, but at the same time, there is a significant increase in the chance of having multiple pregnancies, including higher-order multiple pregnancies.

  • Suppose we can select the embryos by blastocyst culture. In that case, we can transfer fewer embryos and still get a better pregnancy chance. We can reduce the chance of multiple pregnancies significantly.

  • Also, for patients who opt for preimplantation genetic testing PGS/PGD – PGT-A, PGT-M, PGT-SR technique, we have to do blastocyst culture and transfer of normal blastocyst.

Who can benefit from Blastocyst culture?

Blastocyst culture may be recommended for women with:

  • A history of multiple failed IVF cycles.
  • Planning to conceive single pregnancy. 
  • A history of miscarriage.

When is Blastocyst culture recommended?

Blastocyst culture is recommended for all women undergoing IVF. All patients where selection of embryo is possible, blastocyst culture is recommended. If there are very less number of embryos then blastocyst culture decision should be taken after consultation with your doctor. 

What are the benefits of Blastocyst culture and transfer?

There are several benefits to blastocyst culture and transfer, including:

  • Increased chances of implantation and pregnancy: Blastocysts are more likely to implant in the uterus and result in a pregnancy than earlier-stage embryos.
  • Reduced risk of multiple pregnancies: Because only one or two blastocysts are typically transferred, the risk of multiple pregnancies is lower than with earlier-stage embryos.
  • Improved selection of healthy embryos: Blastocysts have undergone more development than earlier-stage embryos, which allows for a better assessment of their health and potential for implantation.
  • PGT: PGT  is a procedure that can be used to identify genetic abnormalities in embryos before they are transferred to the uterus. Blastocyst culture is necessary for PGT.

What are the risks of Blastocyst transfer?

There are also some risks associated with blastocyst culture and transfer, including:

  • The risk that the embryos will not survive to the blastocyst stage: Not all embryos will develop into blastocysts.
  • The risk of miscarriage: Even if a blastocyst implants in the uterus, there is still a risk of miscarriage.


The number of embryos that reach the blastocyst stage varies depending on the woman’s age and other factors. In general, about 30-60% of embryos will develop into blastocysts.

Vary depending on individual factors, but generally higher than earlier-stage embryo transfers.

Yes, there is usually an extra cost for blastocyst culture and transfer. This is because it is a more complex procedure than transferring earlier-stage embryos.

The wait time can feel agonizing, but it usually takes 10-14 days after blastocyst transfer to get a definitive answer. This is because it takes time for the embryo to implant in the uterus and start producing detectable levels of pregnancy hormones. Most clinics pregnancy blood test around this time, confirm the results.

While there’s no guaranteed formula for success, some lifestyle changes might be beneficial:

Before Transfer:

  • Maintain a healthy weight: Aim for a balanced diet and regular exercise.
  • Reduce stress: Consider relaxation techniques like yoga or meditation.
  • Stop smoking and limit alcohol: These can negatively impact fertility.
  • Optimize sleep: Aim for 7-8 hours of quality sleep nightly.

After Transfer:

  • Avoid strenuous activity: Opt for gentle walks or light exercise.
  • Stay hydrated: Drink plenty of fluids throughout the day.
  • Maintain a positive attitude: Stress can hinder implantation.
  • Listen to your body: Rest when needed, but don’t become obsessed with symptoms.

Remember, these are general recommendations, and your doctor may have specific advice based on your individual situation.

Several factors affect success rates, including:

  • Age: Younger women generally have higher success rates.
  • Embryo quality: Healthy blastocysts with good morphology are more likely to implant.
  • Number of embryos transferred: One or two blastocysts typically offer the best balance of success and risk of multiples.
  • Underlying medical conditions: Certain conditions can impact implantation success.
  • Uterine lining health: A healthy lining is crucial for embryo implantation.

Unfortunately, this can happen, but it doesn’t mean there aren’t options.

  • Repeat IVF cycle: Adjustments can be made to improve embryo development in future cycles.
  • Freeze remaining embryos: If some embryos develop further, they can be frozen for later transfer.
  • Consider alternative embryo transfer: Earlier-stage embryo transfer might be an option.
  • Seek genetic testing: Identifying potential genetic issues can inform future treatment decisions.

While older women generally have lower pregnancy rates, blastocyst culture can offer some advantages:

  • Improved embryo selection: Allows for identification of healthier embryos with higher implantation potential.
  • Reduced risk of multiples: Fewer blastocysts are typically transferred, minimizing the risk of multiples associated with higher pregnancy rates in older women.

However, it’s important to remember that age remains a significant factor in pregnancy success, and blastocyst culture doesn’t guarantee success.

If embryos don’t develop to blastocysts, alternative options include:

  • Transferring earlier-stage embryos: Cleavage-stage embryos (day 3) or blastocyst-stage embryos frozen from a previous cycle.
  • Advanced fertilization techniques: you may consider advanced techniques like pICSI or Spindle view icsi to get better embryos that have higher probability of reaching up to blastocyst stage.
  • Donor eggs or embryos: If your own eggs are unable to produce viable embryos.

Ultimately, the best course of action depends on your individual circumstances and preferences. Discussing these options with your IVF doctor can help you make informed decisions.

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