Interrelations among the characteristics of human semen, and a new system for classification of male infertility.

The clinical fertility of 1077 men who underwent semen analysis during the years 1950 to 1952 was studied 20 years later using questionnaires returned by 785 men (72.9%). Decreasing fertility was correlated with decreasing sperm count (P less than 0.01), with increasing numbers of immobile sperm (P less than 0.01), with poorer motility (P less than 0.01), and with increasing numbers of morphologically abnormal sperm (P less than 0.01). The characteristics mentioned were all interrelated (P less than 0.01), with correlation coefficients from 0.36 to 0.67. A new system for classification of male fertility potential is elaborated, using a combination of the four characteristics. This system expresses the fertility of the man and the couple as a percentage of the chance of obtaining living children.