Has the fertility of Danish men declined through the years in terms of semen quality? A comparison of semen qualities between 1952 and 1972.

The semen analysis of 1,077 men examined in 1952 was compared with the semen analysis of 1,000 men examined in 1972 in order to assess if fertility in Danish men has declined during the period. The men on both occasions were examined because of a fertility problem. In 1952 6.2% of the men had azoospermia compared with 3.9% in 1972 (P less than 0.05). Between 1952 and 1972 there was a fall in sperm count (P less than 0.01, median 73.4, and 54.5 mill/ml), a deterioration in spermatozoa motility (P less than 0.001), an increase in number of abnormal spermatozoa (P less than 0.01, median 26.0%, and 44.8%), and a deterioration in fertility class according to the Hammen system (P less than 0.001). Semen volume and number of immobile spermatozoa did not change. This study of Danish men, like studies from other industrialized countries, indicates a fall in semen quality and male fertility since the early fifties.