Many people prefer hot baths, especially in the north, but a long-term hot bath may have a reduced fertility for men. This is because a long-term hot bath will make the testicles too hot, affecting the production of sperm, leading to a reduction in their number and further affecting male fertility. The number of patients with infertility has increased dramatically, and abnormalities in sperm quality are becoming more prominent, with a clear trend toward younger age. The decline in sperm quality is caused by many reasons, and the negative effects on sperm caused by small things in daily life cannot be ignored. Sperm production begins in the testicles, which are very sensitive to temperature, with an optimum temperature of 34°C, 2 to 3°C lower than the normal body temperature of the human body, which is most conducive to sperm production. If the temperature is too high will have an adverse effect on testis IX and damage the sperm production function. To ensure the right temperature, males and other male mammals have an external “pouch”, the scrotum, to provide a lower temperature for the testicles. The cold temperature of the scrotum ensures that the testes are able to produce good quality sperm and also facilitates the storage of sperm in the epididymis. Some infertility patients have higher than normal scrotal temperatures, especially men with varicocele or idiopathic infertility, whose testes are warmer than those of normal fertile men, which can affect sperm production in the testes in the long run. In addition to providing an envelope to protect the testes, the body also provides an adapted ambient temperature for this purpose. The following five features make it physiologically possible to maintain low temperatures in the testes: (1) the sarcoid muscle; (2) the levator muscle; (3) the countercurrent heat exchange system of the blood vessels; (4) the absence of a fatty skin layer; and (5) a large number of sweat glands. A hot bath puts the scrotum, which encases the testicles, in high temperature, and the scrotum is affected by the high temperature, disrupting its thermoregulatory balance, thus triggering thermal damage to the sperm. Prolonged hot baths lead to high testicular temperature, which seriously affects sperm production. Therefore, the temperature of bathing water should be controlled at around 30°C. You should wash your pubic area with cold water every day, which is also good for preventing inflammation caused by foreskin scale, and also pay attention not to use soap and other cleaning pubic area, which can easily destroy the urethra autoimmune environment and easily cause inflammatory reactions. Some of the ingredients in the soap may also kill sperm, so you should use water or male specific lotion, etc. One study found that for 3 days in a row, soaking in warm water at 43-44C for 20 minutes, the original sperm concentration of normal people, sperm concentration can drop to less than 10 million bars/ml, and this can last for 3 weeks. Therefore too frequent and too long hot baths or saunas are inappropriate for infertile patients with low sperm count and low viability.