In 1954, the first successful pregnancy was achieved by applying frozen semen for artificial insemination. Before freezing, semen needs to be mixed with cryoprotective solution, and before clinical use, it must also be thawed and processed. The cryopreservation process consists of three important processes: freezing, storage, and thawing. The main link to damage sperm viability and quality lies in the freezing, recovery process. Cryoprotection can lead to a decrease in semen quality, and when the sample is thawed, sperm viability and morphology are impaired, including damage to the mitochondria, acrosome, and tail of the spermatozoa. Recent studies have confirmed that sperm freezing decreases viability by 31%, 37% have morphological damage, and 36% decrease in mitochondrial activity. Viability is the most important factor that may affect the success rate of frozen-thawed sperm for IUI and IVF. The purpose of semen cryopreservation is to avoid situations where semen is not available or not enough sperm can be retrieved on the day of egg retrieval or at the time of IUI for various reasons. The quality of sperm (density, viability, etc.) will decrease after the semen has been frozen and recovered. This is due to differences in sperm quality and the ability of sperm to tolerate freeze resuscitation due to differences between each individual. No sperm may survive after resuscitation due to damage to the sperm from freezing, and the hospital will still charge for freezing and preservation fees. If the sperm quality is poor after thawing and recovery, artificial insemination treatment may not be possible; or conventional in vitro fertilization may not be performed and only single sperm follicular plasmapheresis may be performed; or even the next step of treatment may not be possible due to the absence of motile sperm. It is recommended to collect fresh semen from the husband and use frozen semen only as a last resort. Based on the current state of medical care, there is no guarantee that every IVF/IUI fetus using frozen semen will be healthy and there is a risk of miscarriage, ectopic pregnancy, preterm delivery, fetal malformation and other pregnancy and delivery complications after pregnancy. Which patients need semen cryopreservation? 1. Semen cryopreservation at the Fertility Center is only for patients who intend to undergo IUI or IVF at the Center; 2. Patients who have difficulty in masturbating to retrieve sperm, freezing the sperm backup to relieve the pressure of sperm retrieval on the same day, and using the fresh semen retrieved if the retrieval is successful on the day of egg retrieval; 3. Patients who have difficulty with penile erection, especially those who tend to have difficulty with penile erection in the hospital; 4. Patients who are not used to masturbating to retrieve sperm and need to go through sexual intercourse to remove Patients who are prone to anxiety and tension; 6. Patients who are older (over 40 years old), with hypertension and diabetes, and other cardiovascular history, are prone to erectile difficulties on the day of egg retrieval, resulting in failure of sperm retrieval; 7. The male partner often travels, lives abroad or abroad, and cannot come to retrieve sperm on the day of egg retrieval; 8. The female partner does natural cycles or microstimulation cycles and is expected to do several cycles, and the male partner cannot guarantee that he can come over for sperm retrieval every time; 9. Some patients with very severe oligospermia and weak spermatozoa, where active sperm are sometimes seen in the semen and sometimes not; 10. Patients with obstructive azoospermia have sperm obtained from the testes, epididymis or distal vas deferens through surgical procedures; 11. Patients with non-obstructive azoospermia have sperm obtained from the testes through microsurgery 12. Progressive decline in sperm quality due to disease or treatment regimens taken to treat disease with the potential to cause azoospermia (pituitary microadenoma, craniopharyngioma).