Sperm vitality A plus B, is an important indicator used to determine sperm activity. If the percentage of sperm count in the A plus B level is greater than or equal to 42% or more, it is a normal level, indicating normal sperm viability. If it is less than this value, it means that the sperm activity is low. Low sperm vitality can easily cause weak spermatozoa, resulting in male infertility. The vitality of sperm can be divided into four grades according to the vitality, which are grade A, B, C and D. Among them, A and B two levels of sperm, are sperm in a straight forward motion, C lineage level of sperm lost in situ spinning sperm, D level of sperm is often inactive. So A plus B two levels of sperm, indicating forward-moving sperm, when that ratio is at normal levels, sperm vitality is considered normal.