Inactive sperm indicate that the sperm are also less active. In normal human semen, there are also sperm of slightly poorer quality, but the percentage must not be too high. Clinically, sperm are classified into 4 classes, Class A sperm move forward and have very strong linear motion activity, Class B sperm move forward but in an irregular direction and move slowly, Class C sperm do not move forward, but in any direction, and Class D sperm basically wriggle or vibrate in place. It is generally believed that normal sperm motility should be >25% for class A sperm, or >50% for class A sperm plus class B sperm for normal pregnancy. So if there are too many inactive sperm, that is, class D sperm, it can affect fertility. There are five general causes: 1. high temperature environment. 2. inflammatory infection of the reproductive tract especially epididymitis. 3. lack of nutrition and poor health of the patient himself. 4. prolonged abstinence can also lead to reduced sperm vitality. 5. high mental tension and anxiety of the patient himself. This kind of reason can also explain why many people have normal checkups and normal bodies, but couples who are eager to have children just can’t get pregnant because of the high level of mental tension.