1. Infection Acute and chronic inflammation of the reproductive tract or reproductive glands, such as the epididymis, vas deferens, seminal vesicles and prostate, can reduce the motility of sperm. The effect of infection on sperm motility can be multifaceted. The direct effect of microorganisms on sperm, such as mycoplasma, can attach to the head, mid-section and tail of sperm, causing increased hydrodynamic resistance and slower movement when sperm make forward motion, affecting sperm viability and the ability to penetrate egg cells. In addition, mycoplasma can cause partial sperm membrane defects or even membrane structure destruction, affecting the fertilization ability of sperm. E. coli can reduce sperm viability by binding to sperm through its own receptors; the indirect effect of microorganisms on sperm can be through the production or release of toxic substances, and mycoplasma produces NH3 during growth to have a direct toxic effect on sperm. Escherichia coli can produce sperm braking factor. Decreased sperm viability due to infection can also be achieved by changing the pH of seminal plasma, which decreases significantly when the pH is below 7 or above 9. In patients with acute adnexal inflammation or epididymitis, the pH is more alkaline, while chronic adnexal inflammation can cause the pH to fall below 7. In addition, inflammation-induced leukocytosis in semen can lead to a decrease in sperm motility through direct and indirect causes. The lack of sperm motility caused by prostatitis may be the result of a combination of factors, which may be related to zinc disorders in addition to microorganisms, leukocytes and pH. 2, abnormal semen liquefaction Semen non-liquefaction or high viscosity is one of the causes of male infertility, a very important factor which may cause infertility by affecting the motility of sperm. In seminal plasma with non-liquefied semen, elongated fibrin may be seen and intermeshed to reduce the space for sperm movement, and sperm are held back, while coarse fibers are seen connected by many fine fibers in a network, which may be responsible for mechanically limiting forward movement of sperm. The authors of this paper have used urokinase-type fibrinogen activator (uPA,) alone on specimens of non-liquefied semen in vitro and found that when the semen changed from non-liquefied to liquefied state, sperm viability and forward motility increased significantly, and the same effect was obtained with chymotrypsin. 3. Immune factors Anti-sperm antibodies (AsAb) can affect the fertilization function of sperm from several different ways. The effect on sperm motility may be due to the binding of AsA b to the tail of the sperm, which impedes sperm motility and reduces the ability to move and penetrate, which has been confirmed by the fact that the ability to penetrate the cervical mucus is significantly reduced when anti-sperm antibodies are present against the tail of the sperm. Some scholars have used AsAb positive serum and human sperm contact, observed a so-called sperm “shaking phenomenon” (shaking phenomenon, mainly the head and the entire tail of the sperm combined with anti-sperm antibodies, the forward motion of sperm suppressed, but no significant changes in survival rate. Gonzales et al. found that prolactin in seminal plasma has a linear relationship with sperm activity, which increases sperm oxygen uptake or affects sperm viability through the cAMP system. Excessive testosterone in seminal plasma may inhibit sperm motility. 5, syndrome In the early 1930’s Kahl was the first to discover a condition that was later confirmed by other scholars to be a congenital lack of cilia structure, manifested by the inability of the cilia of each ciliated cell in the body to move, mainly the cilia power protein arm of the peripheral microtubules (dynein alms, deficiency. Patients with this syndrome may have chronic respiratory infection disorders traced from their medical history, in addition to the inability of sperm to move. 6. Chromosomal abnormalities Autosomal and sex chromosome aberrations affect sperm viability and forward motility in addition to sperm count. The ultrastructural apparatus known to be associated with sperm motility can have abnormal sperm tail structure due to genetic factors, for example, lack of inner or outer branching arms or absence of both arms. There can also be a lack of central junctions and central complex structures, as the interaction between the central microtubules and the radial spokes can mediate the gliding of the outer microtubules, and when this structure is abnormal, sperm motility can be impaired. Varicocele can lead to male infertility in several ways, not only by affecting the occurrence of spermatozoa, but also by causing a decrease in sperm motility. The mechanism may be due to blood stagnation in the varicose veins, impaired microcirculation, lack of nutrient supply and reduced partial pressure of oxygen, insufficient energy production and endocrine dysfunction. In addition, it may also be caused by varicocele, which leads to autoimmunity such as the production of anti-sperm antibodies and mycoplasma infection indirectly causing the decrease of sperm vitality. 8, other factors 1, trace elements: seminal plasma zinc, copper, magnesium and semen quality, seminal plasma zinc content is more than 100 times the plasma content, low sperm vitality patients in the seminal plasma zinc, iron, magnesium content is significantly lower than the vitality of normal healthy men. Zinc delays lipid oxidation of cell membranes and maintains the stability and permeability of cell structures, thus ensuring good sperm motility. Trace elements cadmium (Cd, when the content is high, can lead to reduced sperm motility, cadmium can directly inhibit sperm oxidase and direct inhibition of sperm motility organs, infertile men’s semen cadmium content is significantly higher than that of fertile men. 2, the lack of enzymes or reduced enzyme activity related to sperm motility, vitamin class deficiency, engaging in high temperature, radiation occupations and exposure to chemical toxins can cause a decrease in sperm vitality. 3, smoking, alcohol consumption and drug factors: tobacco nicotine and other direct and indirect damage to sperm through the sperm and affect sperm vitality, long-term alcoholics can directly and indirectly affect sperm motility, affect sperm vitality of more drugs. There are also some people with low sperm motility whose cause cannot be detected, called idiopathic weak spermatozoa.