What are the mysteries of the magical frozen embryos? 1. What is frozen embryo? Does it mean putting the baby into the refrigerator? This refrigerator is not the other refrigerator ~ embryos will be placed in a special cryoprotectant, and after treatment, placed in liquid nitrogen at -196℃. At such a low temperature, the embryos are metabolically quiescent and can be stored for a long time. When the cryoprotectant is replaced at the time of rewarming, the embryos can regain their activity. 2. How long can embryos be frozen? There is no uniformity in the time frame of embryo freezing. Internationally, there are cases where embryos have been frozen for as long as 20 years with successful pregnancies, and recently, there are reports of second births in China with embryos frozen 10 years ago. However, in general, domestic norms recommend freezing for no more than 5 years. 3. In what cases should I choose frozen embryos? Will the pregnancy success rate be lower than that of fresh embryos? Firstly, during conventional IVF treatment, multiple eggs are obtained through ovulation and multiple embryos may be formed. However, only 1-2 embryos are transferred in a cycle and the extra embryos are frozen and can be used for future transfers. Secondly, because ovulation promotion tends to cause temporary abnormalities in the body’s sex hormone environment, making the endometrium unsuitable for embryo implantation in that month. Freezing the embryos at this time and transferring them later when the endometrium is ready can, on the contrary, improve the success rate of IVF. Third, the risk of ovarian hyperstimulation is higher when fresh embryos are transferred in a superovulatory cycle, and the safety of the mother is better ensured when frozen embryos are transferred in a non-superovulatory cycle. 4. The baby will not freeze and become a sleeping beauty, right? Of course not, because the fertility center has a “prince” to wake up the sleeping beauty. Embryo freezing and thawing is really demanding for embryologists, laboratory environment and equipment. Only experienced embryologists are capable of doing this. The successful recovery of embryos is closely related to the quality of the embryos themselves and the operation of the laboratory. Our center currently has a frozen embryo recovery rate of over 98%. 5. Are the babies born from frozen embryos healthy? From the current research results, frozen embryos do not increase the birth defects and health risks of the offspring, and are the same as the offspring born from fresh embryos and natural conception. 6.I am not planning to have a baby yet, but I am worried that I may have difficulties or be too old to have a baby in the future, can I freeze my sperm, eggs or embryos first? Freezing sperm, eggs or embryos is indeed an effective way to preserve fertility. These techniques are also relatively mature. However, these freezing techniques are still recommended in our country for fertility difficulties for medical reasons, and the freezer needs to comply with our current ethical principles of assisted reproduction.