Embryo Freezing and Preservation: How It Works and What It Costs

Reviewed By: Dr. Usha Brindhini, fertility specialist at Ferty9 Fertility Clinic, Kukatpally

Embryo freezing offers a promising pathway for preserving fertility and future family planning. By safeguarding surplus embryos created during assisted reproductive techniques, individuals can hold onto the opportunity to conceive at a later time.

After embryo transfer, there are often some good-quality embryos left over after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).  Instead of discarding them, embryo preservation allows embryos to be frozen and stored for future use. Embryos can also be frozen to preserve fertility, making it feasible to conceive a baby later on. 

Embryos are typically frozen at specific stages of their development. Most commonly, embryos are cryopreserved at the cleavage stage—usually on Day 2 or Day 3, when they have 4–8 cells—or at the blastocyst stage, generally on Day 5 or Day 6, when the embryo has expanded and formed distinct cell types (the inner cell mass and trophectoderm) . .

What is Embryo Freezing?

Embryo freezing is a fertility preservation method used during in vitro fertilization (IVF). In this process, eggs are retrieved from a woman’s ovaries and fertilized with sperm in the laboratory to create embryos. Instead of using all the embryos immediately, one or more high-quality embryos can be frozen for future use. Later, these frozen embryos can be thawed and implanted in the uterus, offering an option to conceive when the time is right. This technique supports family planning and helps maintain fertility over time.

Why Choose Embryo Freezing?

The ability to freeze and thaw embryos using vitrification is one of the most significant developments in ART (Assisted Reproductive Technology) to date. Freezing technology, known as vitrification, has advanced to the point that frozen embryos can now offer patients success rates similar to fresh embryos. Not all patients will have embryos available for freezing following a new IVF cycle, those with a healthy ovarian reserve have a strong chance of preserving embryos for future FET ( Frozen Embryo Transfer) cycles.

You can choose to freeze excess embryos and use them later if you

•  Postpone or cancel implantation into your uterus after a complete fertilization of embryo
•  If you want to postpone IVF until a later date
•  Want an option in case early fertility treatments fail
•  .Preimplantation genetic diagnostics (testing)

The Embryo Freezing Process: Step by Step

Freezing embryos is a safe and effective procedure that often leads to a healthy pregnancy and baby. The success rates of embryo transfe r depend on various factors, including maternal age, embryo quality, underlying medical conditions, and the expertise of the fertility clinic.  

Below is a step-by-step guide to the embryo-freezing process.

Step 1: Hormonal Stimulation for Egg Retrieval

In order to increase the amount of mature eggs accessible for fertilization, the ovaries are stimulated with precisely controlled hormone doses triggered through injection. This process usually involves administering FSH (follicle-stimulating hormone) and LH (luteinizing hormone) analogs over several days, with regular ultrasound and blood tests to monitor follicle development, optimize retrieval timing, and ensure the best possible outcome..

Step 2: Fertilization in the Lab

A semen sample is collected just before the egg retrieval.  The recovered eggs are placed in a laboratory dish containing motile sperm, and fertilization occurs.  Embryos are typically frozen five to six days after the egg retrieval procedure. Day 5 embryo freezing is a widely used technique in IVF, allowing blastocysts to be preserved for future implantation while optimizing success rates. Preimplantation genetic screening (PGS) or diagnosis (PGD) can only be performed once the embryo has reached the blastocyst stage, as cleavage-stage embryos are not suitable for these genetic tests..

Step 3: Cryopreservation Using Vitrification

The primary goal of embryo freezing is to preserve them for future use. One of the biggest challenges in this process is the water inside the cells. If frozen improperly, it can form ice crystals that may rupture the cells, compromising the embryo's viability. To prevent this from happening, the embryologists use a process called cryopreservation. It involves replacing the water in the cell with a substance called a cryoprotectant. On day 5 of embryonic development, after fertilization, embryos at the blastocyst stage can be preserved via cryopreservation for future use in frozen embryo transfer cycles. This process is typically achieved using vitrification, a rapid freezing technique that quickly lowers the temperature to prevent ice crystal formation, thereby safeguarding the embryo’s integrity for later use.

Step 4: Storage in Liquid Nitrogen Tanks

To enhance survival rates, this method utilizes liquid nitrogen to rapidly freeze the embryo, minimizing the risk of ice crystal formation. Once frozen, the embryos are stored in a liquid nitrogen container. This process is known as vitrification-based cryopreservation.

How Long Can Embryos Be Stored?

. A properly frozen embryo can be viable for many decades.  In India, the Assisted Reproductive Technology (Regulation) Act, 2021, stipulates that donor gametes or embryos can be stored for a maximum of ten years. After this period, with the consent of the commissioning couple or individual, they may be allowed to perish or be donated to a registered research organization. 

Benefits of Embryo Freezing

The key benefits include

• With frozen embryos, you have more options for transfer and, thus, more pregnancy attempts.  If you can freeze and keep embryos while attempting a fresh cycle transfer, you can try again without having to endure additional ovarian stimulation or egg retrieval.  As a result, a single IVF round boosts your overall pregnancy rate.
• The ability to freeze embryos for future attempts significantly reduces the physical and emotional toll on patients since they can access their embryos without having to go through the entire process again
• Following a fresh IVF cycle, subsequent FET cycles are less costly because the medication is relatively minimal, and there is no egg retrieval or anesthesia
• Additionally, embryo freezing has helped lower the incidence of multiple pregnancies by allowing the transfer of a single embryo at a time while safely preserving the remaining embryos for future use
• Frozen embryos are available for genetic testing.  Preimplantation genetic screening, or PGT-A, is a test that examines an embryo's chromosomal composition.. Preimplantation genetic screening (PGT-A) and preimplantation genetic testing (PGT) examine an embryo's chromosomal makeup to identify aneuploidies and specific genetic disorders. Only embryos that are free from these abnormalities are selected for transfer, thereby improving the chances of a healthy pregnancy.
• Another significant benefit of being able to freeze embryos is the ability to better plan motherhood, which is critical for women with cancer or other diseases that require them to postpone pregnancy

Risks and Limitations of Embryo Freezing

Repeated freezing and thawing may impact embryo quality; however, embryo freezing itself carries minimal risks or limitations. Although modern vitrification techniques have greatly improved embryo survival rates, a small percentage of embryos may not survive the freeze-thaw process, potentially impacting future transfer outcomes. Additionally, the long-term effects of cryopreservation are still being studied, and there may be financial and regulatory considerations related to storage duration and costs..

The Cost of Embryo Freezing and Storage

The cost of embryo freezing varies greatly based on the fertility center and your location. Costs associated with freezing embryos include early hormone treatments, egg pickup, fertilization, embryo culture, freezing, and storage. Some medical insurance policies cover assisted reproduction treatments. One IVF cycle costs 1.5 lakhs to 2 lakhs. Embryo freezing for a straw, 2 embryos, costs 25000. 

Advances in Embryo Freezing Technology

Advancements in embryo freezing technology, including microfluidics, cryoprotectants, and vitrification, have significantly improved embryo quality and survival rates.  

• Vitrification: The most widely used embryo freezing technique involves ultra-rapid freezing to prevent ice crystal formation. By utilizing high concentrations of cryoprotectants, this method enhances thawed embryo quality and improves survival rates.  
• Microfluidics: These specialized devices help maintain optimal environmental conditions during freezing and thawing, preserving ovarian tissue.  
• Cryoprotectants: These protective substances safeguard embryos from potential damage during the freezing process.  

These advancements have had a profound impact on fertility preservation, increasing the success rates of assisted reproductive treatments. Further advancements in embryo freezing include AI-driven embryo selection, closed-system vitrification for safer storage, and automated freezing systems for precision. Improved cryoprotectants, laser-assisted hatching post-thaw, and enhanced freezing techniques have significantly increased embryo survival and implantation rates.

Wrapping Up

Embryo freezing offers couples a beacon of hope for their future. By preserving precious embryos, families can plan their journey on their own terms. With advanced technology and improved success rates, this embryo-freezing option paves the way to lasting happiness and the dream of welcoming a new life.