How Long Can Embryos Be Frozen and Still Be Viable?

Here is everything you need to know about embryo freezing: the science that provides the option to freeze embryos has transformed the medical field, offering various individuals or couples the ability to preserve their fertility, and grow their family at their own pace. Here at Reproductive Fertility Center, we are proud to offer this service to prospecting couples and individuals.

In this article, we will tour not only the science behind embryo freezing, but also the factors that go into influencing embryo viability, the safety of long-term storage, and other essential details.

What is Embryo Freezing?

Embryo freezing, or embryo cryopreservation, is the process of preserving embryos at sub-zero temperature for future use. What happens is the embryo is frozen at a fixed stage of development; this is done typically between Day 3 and Day 5, subsequently to fertilization. The embryo is most stable at this stage as it has developed into a blastocyst – a crucial point for freezing.

How is Embryo Freezing Done?

Embryos must undergo a careful preparation process prior to being frozen. The process is comprised of the following critical steps:

1. Cultivation: Fresh embryos are cultivated in a specialized growth medium until they reach the blastocyst stage.
2. Dehydration: Embryos are then dehydrated to prevent ice crystal formation, which damages the cells. A cryoprotectant is then used to replace the water inside the cells.
3. Freezing Method: There are two primary freezing methods used:

• Slow Freezing: Embryos are gradually cooled over a few hours; this method was commonly used in the past.
• Vitrification: This newer method rapidly freezes embryos, significantly reducing the chances of ice crystals forming. Vitrification has become the gold standard in embryo cryopreservation due to its higher success rates.

Once frozen, the embryos are stored in liquid nitrogen at temperatures around -196°C, where they remain dormant until needed.

How Long Can Embryos Be Frozen and Remain Viable?

According to a meta-analysis completed by NIH (National Library of Medicine), the length of embryo storage was indicated to not significantly impact viability, implantation, pregnancy, birth outcomes, or birth abnormalities. The analysis suggests that storage times do not adversely affect the potential successful pregnancies.

It is suggested that embryos can remain viable after being frozen for extended periods, with successful pregnancies reported even after storage durations exceeding a decade.

It’s important to note that individual outcomes can vary based on factors such as embryo quality at the time of freezing, the freezing and thawing techniques used, and the age and health of the person undergoing the embryo transfer.

Are There Limits to How Long Embryos Can Be Stored?

Per scientific insights, there is no conclusive expiration date for frozen embryos, as long as they remain stored at proper cryogenic temperatures. According to research, embryos may theoretically remain viable indefinitely, with the exception that they are well frozen and properly maintained.

Moreover, according to a recent study published in Fertility and Sterility, it was reported that embryos frozen for over 20 years have been successfully thawed and implanted, resulting in healthy pregnancies.

Though, it’s essential to note that the quality of the embryo at the time of freezing, along with the specific cryopreservation methods used, plays an imperative role in long-term viability.

Factors That Affect Embryo Viability Over Time

It’s important to note that the technology behind embryo freezing is indeed highly reliable, however there are various factors that may influence the viability of frozen embryos:

• Embryo Quality: The overall health and quality of the embryo at the time of freezing are crucial. High-quality embryos have a better chance of surviving the freezing and thawing process and implanting successfully.
• Freezing Method: Vitrification, the newer and faster method of freezing, offers better results than slow freezing because it minimizes the risk of ice crystals forming in the embryo.
• Storage Conditions: Embryos must be stored in a stable environment with consistent cryogenic temperatures. Any fluctuation in temperature could reduce their viability.
• Thawing Process: Proper thawing is just as critical as freezing. Fertility clinics follow precise protocols to gradually bring the embryo back to room temperature without damaging it.

What Should You Consider Before Freezing Embryos?

If you're considering freezing embryos, there are multiple practical and personal factors to think about. Here are 3 important elements to consider:

• Age and Embryo Quality: Age plays a grand role in the quality of the eggs used to create the embryos. Freezing embryos at a younger age can improve the chances of a successful pregnancy later on.
• Number of Embryos: Some patients choose to freeze multiple embryos to improve their chances in the future. Discussing this matter with your fertility specialist will help you decide how many embryos you should freeze.
• Future Plans: Consider how long you might want to store the embryos. Some individuals choose to store embryos for future family planning, while others may be preserving their fertility for medical reasons (e.g., cancer treatment).

What Happens If You Decide Not to Use Frozen Embryos?

This is a significant ethical and emotional consideration for individuals or couples who decide not to use their frozen embryos. Luckily, there are a few options available:

1. Embryo Donation: You can choose to donate your embryos to another couple struggling with infertility.
2. Embryo Research: Some opt to donate their embryos for scientific research.
3. Thaw and Discard: Another option is to have the embryos thawed and discarded if no longer needed.

These options may be discussed with a counselor or your fertility clinic to help you make the best decision for your family and future.

How to Ensure Your Frozen Embryos Are Safe and Viable for Future Use

Once you’ve decided to freeze embryos, ensuring their safety and viability for future use becomes a priority. Here’s what you can do ensure their safety:

• Choose a Reputable Fertility Clinic: The success of embryo freezing largely depends on the expertise of the clinic. Select a clinic with a strong track record in cryopreservation.
• Regular Monitoring: While frozen embryos are typically safe in storage, regular checks by your fertility clinic ensure they remain properly stored.
• Plan Ahead for Embryo Thawing: The thawing process is just as crucial as freezing. Make sure your clinic has expertise in thawing embryos to maximize their chances of survival and implantation.

Conclusion

Embryo freezing offers remarkable flexibility for individual persons and couples looking to preserve their fertility. Thanks to the latest advancements in cryopreservation, Reproductive Fertility Center is able to offer these services to people of all backgrounds. Medical Director, Dr. Peyman Saadat, continues to contribute to the medical community through his years of involvement in research studies aimed at improving pregnancy rates through the use of fertility treatments.

Whether you're planning for the near future or years down the road, embryo freezing offers a valuable solution. Ready to take the next step? Consult with a fertility specialist today to explore your options and start your journey toward parenthood.