Relation between number of immobile spermatozoa and pregnancies obtained during a twenty-year follow-up period immobile spermatozoa and fertility.

The clinical fertility of 1077 men examined with semen analysis including detection of number of immobile spermatozoa during the years 1950-52 was studied twenty years later with a questionnaire replied by 785 (72.9%). There was a significant relation (p less than 0.01) between decreasing number of immobile spermatozoa and increasing chance of getting living children, but no relation to abortions and pathological pregnancies. Furthermore, decreasing number of immobile spermatozoa was correlated to shorter time-interval between attempt to impregnate and first pregnancy obtained (p less than 0.01). Mean values for those obtaining living children was 34.7% immobile spermatozoa compared with 38.2% for those not doing so. Over 80% immobile spermatozoa, fertility was considerably reduced, and the borderline between normal and reduced male fertility should therefore be defined to 80% immobile spermatozoa.