Introduction: Based on historical data, a decline in sperm counts during the years 1940-1990 has been suggested and aetiologically linked to a concomitant increase in the incidence of testicular cancer. This study, focusing on possible changes in sperm parameters among young Swedish men, during the past 10 years, was specifically designed in order to answer the question of whether there is a continuing decline in sperm counts.
Methods: During the period 2008-2010, 295 young (17-20 years; median 18) men born and raised in Sweden were recruited at the age they were supposed to undergo medical examination prior to military service. The participants filled in questionnaires, underwent andrological examination and delivered an ejaculate. Their semen parameters were compared with those of a similar cohort of men (n = 216) recruited in the year 2000-2001.
Results: No significant changes (means; 2000-2001 versus 2008-2010) in sperm concentration (78 × 10⁶/ml versus 82 × 10⁶/ml; P = 0.54), semen volume (3.1 ml versus 3.0 ml; P = 0.26) or total sperm counts (220 × 10⁶ versus 250 × 10⁶; P = 0.18) were found. The proportion of progressively motile spermatozoa also remained unchanged.
Conclusions: Between the years 2000 and 2010 we found no evidence of time-related deterioration of semen parameters among young Swedish men from the general population. This finding does not exclude that such a decrease may have taken place before year 2000. If the risk of testicular cancer is linked to the sperm counts, the increase in incidence of this malignancy should be levelling off in southern Sweden in the next 10-15 years.