Compared to egg freezing, embryo freezing tends to have a higher success rate as fertilised embryos are more stable during the freezing & thawing process.
In the field of fertility treatment, embryo freezing, also known as cryopreservation, has emerged as a revolutionary technique. Popularised in part by celebrities, it has given women the freedom to balance careers, personal growth, education, and family life without compromising their chance at motherhood. By preserving fertility potential early in life, it safeguards future egg quality and quantity, thereby offering autonomy and control over parenthood.
What is embryo freezing?
In this process, eggs are collected and fertilised with sperm in a laboratory through IVF. The resulting embryos are then frozen at sub-zero temperatures for later use. When the woman is ready to conceive, these embryos are thawed and transferred into the uterus.
Compared to egg freezing, embryo freezing tends to have a higher success rate because fertilised embryos are more stable during the freezing and thawing process.
In short:
- Embryo freezing preserves fertilised eggs (embryos).
- Egg freezing preserves unfertilized eggs.
Reasons to freeze embryos
During ART procedures, some high-quality (Grade A) embryos may be left unused. Instead of discarding them, they can be preserved for later use. Embryo freezing is also a reliable method of fertility preservation.
Key reasons include:
- Delaying motherhood with assurance: Freezing embryos at a younger age allows women to pursue careers, financial stability, or personal goals, while retaining the option of motherhood later.
- Medical necessity: Women undergoing treatments such as chemotherapy, hormone therapy, or other fertility-impacting procedures can preserve embryos beforehand to safeguard their chances of parenthood.
- Preimplantation genetic testing (PGT): Embryo freezing enables testing to lower the risk of inherited disorders.
- Medical precautions in IVF cycles: Doctors may recommend freezing embryos to avoid complications such as ovarian hyperstimulation syndrome (OHSS) or when abnormal hormone levels threaten fresh transfer success.
Today, many people view embryo freezing as a safety measure. It enhances the likelihood of conception later and is particularly valuable for women in their late 20s and early 30s.
When can an embryo be preserved?
- Day 2–3: Two to eight-cell stage
- Day 5–6: Blastocyst stage (most common)
They are stored in liquid nitrogen at around –200°C using a process called vitrification. These frozen embryos can technically be stored for decades altogether.
With vitrification, survival rates of frozen embryos after thawing exceed 99 per cent. Clinical studies confirm that frozen embryo transfers (FETs) achieve pregnancy and live birth rates comparable to or better than fresh transfers. Children born from frozen embryos are as healthy as those conceived naturally.
