Embryo Freezing

The Modern Choice for Fertility Control

What Is Embryo Freezing?

The decision to start a family is not always aligned with the immediate conditions that allow for pregnancy. Modern medicine offers solutions that respect each couple’s timing and individual needs. Embryo freezing is one of the most reliable fertility preservation methods, allowing couples to plan pregnancy at the most suitable stage of their lives. In the era of personalized care and technological advancement, embryo cryopreservation combines scientific precision with emotional reassurance, offering a stable foundation for building a future family.

Embryo freezing has become an integral part of modern assisted reproduction, offering significant advantages to couples who wish to safeguard their fertility for the future. As technology continues to evolve, an increasing number of children are born from cryopreserved embryos, highlighting both the safety and effectiveness of the method. The ability to store embryos for future use provides couples with the flexibility to plan pregnancy according to their personal and medical circumstances, without compromising implantation success rates.

In certain IVF (in vitro fertilization) cycles, more embryos are created than those selected for immediate transfer to the uterus. With the use of advanced time-lapse incubators and strictly controlled culture conditions, high-quality embryos can be developed. In addition, the use of artificial intelligence enhances the process by enabling precise embryo ranking based on implantation potential. Surplus embryos that are not transferred are frozen at the blastocyst stage using the vitrification method, ensuring very high survival and success rates in future cycles.

How the Embryo Freezing Process Works

The embryo freezing process begins with a crucial step: the couple’s informed consent. Before any stage proceeds, specialized consent forms must be signed, clearly outlining key aspects such as where the embryos will be stored, the duration of storage (typically up to 10 years), what happens after the storage period expires, and how the embryos will be managed in cases where no decision can be made or in the event of death.

Additionally, it is determined whether the embryos will be used exclusively for your own fertility treatment or whether they may be allocated for research purposes or donated to other infertile couples. This stage is essential, as it ensures legal, medical, and ethical clarity before the embryo cryopreservation process begins.

Choosing the Embryo Stage for Freezing

Embryo freezing can be performed at two different developmental stages, depending on the medical strategy and embryo quality. At the cleavage stage, embryos have already divided into four to eight cells, about 72 hours post-fertilization. In contrast, at the blastocyst stage, embryos have developed into a more complex structure of 200–300 cells, usually five to seven days post-fertilization. The choice of stage depends on embryo viability, implantation likelihood, and the experience of the medical team. Freezing at the blastocyst stage is considered particularly effective, offering greater certainty about embryo quality and future survival.

Vitrification Process

The most widely used freezing technique is vitrification, which involves ultra-rapid cooling to prevent ice crystal formation and preserve cellular integrity. Initially, a special cryoprotective agent (CPA) is added to the embryos, acting as an antifreeze to protect cell structure. The embryos are then placed directly into liquid nitrogen tanks at -196°C, where they remain in complete dormancy and stability for long-term storage. Each embryo is stored in a separate container (similar to a small straw), which is uniquely labeled to ensure full identification and traceability. This method boasts exceptionally high survival rates upon thawing.

What Happens After Freezing

When the time comes to use the frozen embryos, the thawing process is carried out with great precision. The embryos are removed from liquid nitrogen and gradually returned to normal temperature. The cryoprotective agent is then carefully removed to prevent cellular stress. Finally, the embryos are assessed by the scientific team, and if they meet the required quality criteria, they are transferred into the woman’s uterus during a controlled embryo transfer cycle. A major advantage of this method is that embryos retain the biological age they had at the time of freezing, preserving their quality regardless of how much time has passed.

Embryo Freezing: Who Is It For?

Embryo freezing is a targeted solution for couples who wish to secure their chances of building a family in the future. In cases where more embryos are produced during an IVF (in vitro fertilization) cycle, surplus embryos can be cryopreserved for future use—either to achieve a second pregnancy or as a backup option in case the first cycle is unsuccessful. This approach allows couples to plan their family journey with greater ease and less stress, while maintaining stable success rates.

Application in Preimplantation Genetic Testing (PGT)

Embryo freezing is also essential in cases involving preimplantation genetic testing (PGT), as embryos are kept frozen until the genetic analysis is completed. This period is used to extract valuable information that allows for the selection of embryos free from genetic abnormalities or hereditary conditions. In this way, embryo freezing actively supports the genetic safety of the future child, ensuring that embryo transfer is performed only with healthy genetic material.

Fertility Preservation for Patients Undergoing Medical Treatments

Patients who are about to undergo treatments such as chemotherapy, radiation therapy, or surgeries that may affect fertility can rely on embryo freezing to preserve their ability to have children in the future. This preventive strategy offers hope and a practical solution for individuals facing serious health conditions, allowing them to maintain their family planning regardless of disease progression.

Prevention of Ovarian Hyperstimulation Syndrome (OHSS)

Embryo freezing can also be used to prevent ovarian hyperstimulation syndrome (OHSS), a serious complication of IVF treatment. By adopting a “freeze-all” strategy, immediate embryo transfer is avoided, allowing the body to recover naturally and reducing the risk of complications. This approach enhances both patient safety and the overall success of the treatment.

Embryo Freezing in Cases of Elevated Hormone Levels

Embryo freezing is also recommended for women with elevated progesterone levels during an IVF cycle, particularly when levels exceed 1.5 ng/ml on the day of the ovulation trigger injection (trigger day). This hormonal imbalance may reduce implantation rates by up to 20%, making embryo freezing the safest and most effective option. Delaying embryo transfer and performing it in a future, hormonally balanced cycle significantly increases the chances of a successful pregnancy.

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Advantages of Embryo Freezing

Embryo freezing offers a series of meaningful advantages that boost both IVF effectiveness and safety. One of the most important benefits is the reduced need for repeated ovarian stimulation cycles. When there are surplus high-quality embryos, multiple embryo transfers can be performed without new medications. This means less physical and financial strain on the woman, as additional injections, tests, and procedures are avoided, while pregnancy success rates increase.

Improved Endometrial Receptivity and Medical Safety

Another key advantage of embryo freezing is the ability to transfer them in a later cycle when the endometrium is more naturally prepared. Research shows that the absence of hormonal stimulation leads to improved endometrial receptivity and higher implantation rates. This approach is especially useful when high levels of estradiol or progesterone are observed in the fresh cycle, as these can negatively affect the outcome. Postponing the embryo transfer to a more stable cycle enhances clinical effectiveness and provides additional safety for the woman.

IVF pregnancy anatomy model showing fetal development inside uterus, used during patient education for clear visualization and understanding.

Healthy Pregnancy Outcomes and Child Development

Embryo freezing is a medically proven safe technique, as children born from frozen embryos do not show increased rates of congenital anomalies compared to the general population. Available data confirm that cryopreservation does not negatively affect the child’s future health, reinforcing trust in the technique among parents and professionals. Scientific advancements in vitrification have made the process completely safe and effective, offering long-term solutions without compromising the quality or health of new life.

IVF pregnancy ultrasound review session with patient and specialist, discussing fetal development and confirming healthy progression of pregnancy.

Success Rates of Pregnancies with Frozen Embryos

At FertUlity, we follow a specialized protocol for freezing embryos at the blastocyst stage using advanced vitrification techniques. This method ensures exceptionally high survival rates after thawing — exceeding 95%.

The embryo quality remains unchanged, making the chances of pregnancy comparable to those with fresh embryos. Our data confirm that frozen embryo transfers at FertUlity deliver consistent and reliable results, meeting each couple’s needs with precision and safety.

Embryo cryopreservation is not just an alternative — it’s a strategic choice with high success potential that has helped hundreds of women hold the baby they dreamed of.

The Embryo Transfer Process and Necessary Preparation

Frozen embryo transfer at FertUlity is planned individually to optimize endometrial readiness and achieve pregnancy. The timing of the transfer is based on the so-called “implantation window” — the period during which the endometrium is most receptive.

The woman’s preparation can be done either through a natural cycle by monitoring ovulation or through medication that regulates the cycle and transfer day. In a controlled cycle, taking estrogen pills for 12–14 days helps develop the endometrium properly, which we monitor via ultrasound for thickness and triple-layer texture. Proper uterine preparation is a critical factor for implantation success and subsequent pregnancy.

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Frequently Asked Questions About Embryo Freezing

At what stage do you usually freeze embryos and why?

We primarily freeze blastocysts, as at this stage (5–7 days post-fertilization), they have higher implantation potential and allow us to select the best-quality embryos before cryopreservation.

What are the survival and pregnancy rates after thawing?

Thanks to vitrification, over 95% of embryos survive intact; pregnancy rates are comparable to those of “fresh” embryos, offering a strong success likelihood for each transfer.

How much does embryo freezing and annual storage cost?

The total cost includes the IVF (in vitro fertilization) procedure, embryo cryopreservation, and annual storage fees. The cost of cryopreservation remains the same for surplus embryos that may result after a fresh embryo transfer.

How long can embryos remain stored?

Based on the consent you sign, embryos are typically stored for up to 10 years in liquid nitrogen at -196°C, preserving their biological age at the time of freezing. In certain medical cases, the storage duration may be extended further, in accordance with applicable legislation.

Are children born from frozen embryos healthy?

Yes. Studies show no statistical difference in congenital anomalies compared to the general population, confirming the method’s long-term safety.

Who benefits most from embryo freezing?

Couples with surplus embryos, patients undergoing PGT, individuals before fertility-impacting treatments (e.g., chemotherapy), and women with high hormone levels or at risk for OHSS.

Is medication needed before embryo transfer?

Depending on your cycle, either a natural protocol with ovulation monitoring is followed, or a controlled cycle with medication lasting approximately 12–14 days, allowing the endometrium to reach the optimal “implantation window.”

What happens if the storage period expires or I change my mind?

Your consent form specifies whether embryos will be destroyed, used for research, or donated to another couple. This ensures your wishes are legally and ethically respected, even if you’re unable to decide in the future.

Our Doctors

In an era where fertility requires knowledge, care, and substantial guidance, FertUlity is not an impersonal clinic. It is two people who look you in the eye and accompany you step by step on the journey you dream of.

Dr. Chrysostomos (Makis) Papadopoulos Obstetrician – Gynecologist, MD, PhDc, MIC I

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Dr. Chrysostomos Papadopoulos - Specialist in Infertility, Endocrinology & Menopause in Athens

Dr. Maria Oikonomou Obstetrician – Gynecologist

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FertulityThrough the Words of our Parents

100% genuine, public Google reviews.
Because every fertility journey begins with honesty and trust.

      EXCELLENT  
   Based on 12 reviews 
    
 
 
 
   
 
 
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   Μαρια 
 26 days ago
 
 
  The word "thank you" to Dr. Makis Papadopoulos is too small to describe the gratitude we feel for this man. I am pregnant after IVF, having succeeded on the first attempt, and we owe this exclusively to our doctor. First Contact & Communication: From the very first contact, he won us over with his kindness, enthusiasm and willingness to dedicate as much time as we needed. Willing to explain everything in every detail, he solved every question we had in depth — not even a professor to students would analyze them with such patience and contagiousness! Scientific Training: He is an excellent scientist, with deep knowledge of the subject, a perfectionist and focused professional who leaves absolutely nothing to chance. He designed the right treatment for us, solving every problem down to the last detail, making us feel that whatever problem arises, it is certain that it will be solved. HUMANITY & SUPPORT: The most important thing, however, is his humanity. Communication with him was Immediate and he always had as much time as you needed on the phone to solve every question. He showed a deep, real interest, embracing us not just as a doctor, but as if he were our brother. We highly recommend him to every couple starting this journey. He deserves blind trust! We thank you from the bottom of our hearts for the greatest miracle of our lives!

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   Alexandra 
 52 days ago
 
 
  I don't often write reviews, but I feel that Mr. Makis truly deserves it. From the very first moment, he made me feel safe and confident. He listened carefully to what was on my mind, answered every question I had, and explained everything in a simple way, always based on scientific data. Many times, he even sent me relevant scientific studies so that I could better understand why he was suggesting a particular approach. But what stood out to me the most was that he didn't stop at the appointment. He followed up, was genuinely interested in my progress, and was available when I needed him. This is something you rarely encounter. Fortunately, he returned to Greece. He is one of the few doctors who, beyond their knowledge, remain above all human beings. He makes you feel like he sees you as a person and not as just another incident.

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   Matina 
 69 days ago
 
 
  A big thank you to Dr. Makis Papadopoulos who supported us from day one, who checked every little detail, who explained to us every move-step, every test, every medication for the reason we were doing it and what we would achieve. With incredible experience, knowledge, a lot of patience (because we had two other failed attempts with another doctor) and trust, within 8 months he adapted the protocols for our case and we achieved the positive result and we hold in our arms a priceless diamond. Above all, a rare person, calm and always available to listen to our concerns and reassure us. I highly recommend him!

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   Eva 
 93 days ago
 
 
  Thanks to Dr Makis Papadopoulos, I am now holding my two beautiful babies in my arms! He is a true expert. Professional with a human centric approach, friendly and empathetic, always available to answer our (many many) questions. I trust Dr Makis blindly and, honestly, I cannot recommend him enough!
  
 
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   Ivy 
 100 days ago
 
 
  My experience with Dr. Makis took me from a clinical stagnation to an incredible breakthrough, highly recommend Dr. Makis! Navigating the exhausting world of IVF, you know how devastating it is to watch your protocol dosages go up while your results go down. After three intense, high-dosage cycles with a previous clinic, I was left feeling incredibly discouraged. Despite escalating medications and growth hormones, my blastocyst yield was dwindling, culminating in a heartbreaking round with zero blastocysts. I knew I needed a doctor who didn't just follow a standard script, but who truly understood the nuances of egg quality and customized protocols. That is when I found Dr. Makis. Dr. Makis completely revolutionized my treatment plan. Instead of just pushing maximum dosages, he took a highly strategic, tailored approach. The result? Quality over pure protocol size. While my previous doctors kept increasing the medication dosages (which yielded fewer or zero blastocysts), Dr. Makis completely changed the strategy. He lowered the heavy stimulation, introduced smart egg-quality support (like melatonin), changed the protocol style entirely, and achieved a 700% increase in blastocysts compared to my best previous rounds. Beyond the incredible results, Dr. Makis brings a level of expertise, precision, and reassuring care that is rare to find. He looks at you as an individual, not a statistic, and knows exactly how to pivot when traditional routes fail. If you are looking for a specialist who can turn a difficult prognosis into an overwhelming success, look no further than Dr. Makis. I am incredibly grateful for his care.
  
 
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   Olga 
 111 days ago
 
 
  Dr. Makis Papadopoulos was excellent, professional, and very reassuring throughout the entire process. Thanks to his expertise and guidance, we were able to identify the issue early and take the appropriate steps from the beginning. He took the time to explain everything clearly, answered all our questions with patience, and made us feel comfortable and confident throughout our journey. We truly appreciated his caring approach, professionalism, and dedication. Highly recommended!
  
 
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   Euaggelia 
 122 days ago
 
 
  Dr. Makis Papadopoulos is an excellent scientist and above all a rare person! He is an approachable and smiling doctor, with excellent medical knowledge, who from the first moment I met him made me feel comfortable and trust him completely, answering every question I had with patience and documenting every answer with scientific studies and articles! The most important thing, however, is that Dr. Makis Papadopoulos is always there on the other end of the line to listen to you and reassure you without a trace of haste, a doctor who truly cares and makes you feel like he is your own person! Makis, thank you very much for everything!!! I am very lucky to have met you!

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   Anastasia 
 129 days ago
 
 
  Dr. Makis Papadopoulos is an excellent scientist with a human-centered interest. Our collaboration was excellent from the very beginning and he made me feel confident and secure by explaining every step of the process in great detail. I highly recommend him!

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   Fay 
 131 days ago
 
 
  Dr Makis Papadopoulos is very professional, caring and attentive. Very thorough in explaining the whole process throughout every step. Thank you! Highly recommended!!
  
 
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   Christina 
 134 days ago
 
 
  I would like to share my experience with Dr. Makis Papadopoulos, an outstanding gynecologist and scientist. We first connected in the summer of 2024, while he was based in Germany, through a mutual acquaintance, following a particularly challenging period for us. Prior to meeting him, we had gone through repeated unsuccessful attempts of stimulation and fertilization with other gynecologists. Unfortunately, those approaches relied largely on standardized protocols, without sufficient personalization to address the specific needs of my case. From the very beginning, Dr. Makis stood out for his human-centered approach and his willingness to dedicate time to truly understand our situation in depth. With strong, up-to-date scientific knowledge, he approaches every case holistically, focusing on individualized treatment and adapting protocols to the patient's unique needs. Throughout our collaboration, which now spans approximately two years (with a few breaks on our side), he has consistently been available, supportive, and clear in his guidance. He inspired confidence and helped us stay positive even during difficult phases of the journey. Beyond his scientific expertise, what truly sets him apart is his genuine care for the person behind each case: his empathy, honesty, and continuous effort to achieve the best possible outcome. My husband and I are deeply grateful for his support and guidance, and we now feel ready and optimistic to move forward to the next final stage. We highly recommend him to anyone seeking a gynecologist with true expertise, professionalism, and compassion. I would like to share my experience with Dr. Makis Papadopoulos, an excellent gynecologist and scientist. We met in the summer of 2024, when he was in Germany, through a mutual acquaintance, after a particularly demanding period for us. Before meeting him, we had gone through repeated failed attempts at stimulation and fertilization with other gynecologists. Unfortunately, the approaches that had been followed were mainly based on standardized protocols, without the necessary individualization to the specifics of my case. From the beginning, Dr. Makis stood out for his human approach and his willingness to spend time to understand our case in depth. With modern knowledge and scientific training, he approaches each issue multidimensionally, emphasizing the individualization of treatment and adapting the protocols to the real needs of the patient. During our collaboration, which now spans about two years (with short breaks on our part), he was always available, supportive and clear in his guidance. He inspired confidence in us and helped us remain optimistic even in difficult phases. In addition to his scientific competence, what sets him apart is his genuine interest in the person behind each case: his empathy, his honesty and his constant effort to achieve the best possible outcome. My husband and I thank him warmly for his support and guidance and we now feel ready and optimistic to move on to the next final stage. We highly recommend him to anyone looking for a gynecologist with real knowledge, professionalism and humanity.

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   Faidra 
 135 days ago
 
 
  Dr. Makis Papadopoulos is an excellent gynecologist and above all an excellent person! I truly thank him for his support and care during the egg freezing process. Although my case was particularly demanding, he stood by me with patience, knowledge, great experience and real interest. Our communication was direct and human, while his availability at the many appointments made me feel safe at every step. The protocols were designed specifically for me, aiming for the best possible result, while also taking into account the cost of the medications. I recommend him with all my heart to every woman who wants to trust someone for something so important and sensitive for her.

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   Iliana 
 137 days ago
 
 
  I highly recommend Dr. Makis, he is an incredible specialist. My journey was far from easy, encountering several challenges that  made the process feel overwhelming at times. What sets him apart is his willingness to go beyond standard procedures. He developed a specialized, custom protocol, tailored to my situation, which ultimately made all the difference. Beyond his technical expertise, his calm and clear communication kept me grounded throughout the process. I am so grateful for his persistence and high level of care!

Why choose FertUlity?

Because every fertility journey deserves the right support. At FertUlity, we provide science-based fertility care with a human approach. We support every path, from fertility assessment and preservation to modern assisted reproduction.

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