Embryo freezing, also known as embryo cryopreservation, is a fertility preservation process in which embryos—eggs that have already been successfully fertilized with sperm—are preserved through vitrification and stored at ultra-low temperatures. Using specialized cryoprotectors, embryos are rapidly frozen and stored in liquid nitrogen tanks at –196°C, where cellular activity stops completely, allowing embryos to remain viable indefinitely without deterioration in quality. This option offers several advantages over egg freezing. Because embryos have already passed the fertilization stage, they provide greater certainty regarding developmental potential, allow for pre-implantation genetic testing, and enable couples to plan their families together using embryos created at a specific point in time. The process begins with a comprehensive evaluation of both partners’ fertility. Based on individual characteristics, the medical team designs a personalized IVF protocol. This includes controlled ovarian stimulation over 10–15 days, close monitoring with ultrasound and hormonal testing, and egg retrieval under conscious sedation. Fertilization is performed in the laboratory using conventional IVF or ICSI, depending on sperm quality. After fertilization, embryos are cultured in advanced incubators that allow continuous monitoring without disturbing development. Embryos are evaluated daily as they progress to the blastocyst stage (typically day 5–6), which helps identify those with the highest implantation potential. The best-quality embryos are then vitrified using advanced freezing techniques that prevent ice crystal formation and protect cellular integrity. Frozen embryos are stored in secure, continuously monitored liquid nitrogen tanks. Embryos can remain frozen for many years without affecting future outcomes, and extensive research shows that embryo freezing has no negative impact on the health or development of babies born from frozen embryos. The number of embryos recommended for freezing depends on age and embryo quality; for example, at under 35 years old with good-quality embryos, 2–3 blastocysts may be sufficient, while at older ages or with reduced quality, 4–6 embryos may be recommended. When patients decide to use their frozen embryos, the medical team coordinates uterine preparation and the optimal timing for embryo transfer, followed by specialized monitoring during early pregnancy. Any remaining embryos can be preserved for future attempts or future siblings. If embryos are never used, patients may choose to donate them to other couples or for research, with all decisions made entirely according to their preferences.