What is the sperm activity standard?

Sperm motility

is an important indicator of sperm quality, usually measured by sperm motility score. According to the World Health Organization standards, it is divided into four grades. A sperm can swim quickly to the target, its speed and straightness are higher. B sperm although slower, but still able to move forward, and has a certain straightness. C sperm can only vibrate in place or swing in a fixed position, can not actively move forward. Class D sperm is completely immobile and has no movement.