Changing male reproductive health: A review of the clinical evidence?

Several lines of circumstantial evidence suggest that we may be seeing adve rse changes in male reproductive health. A possible decline in semen qualit y has attracted most attention, but there are stronger indications of a ris ing incidence of testicular cancer, with increases observed in both Europe and the USA. There are striking geographic variations in both the incidence of testis cancer and in the observed rate of increase, and it is noteworth y that testis cancer is much more common in Denmark, where low sperm counts have been reported, than in Finland, where semen quality seems to be bette r. Another cause for concern is the rising incidence of congenital malforma tions of the male genital tract - cryptorchidism and hypospadias. In the UK , for example, rates of cryptorchidism have increased by as much as 65 to 7 7%. The data are harder to interpret on semen quality. In a metaanalysis, C arlsen et al (1992) identified significant decreases over time in sperm con centration, corresponding to a fall of almost 50% between 1940 and 1990. Se veral groups have since examined secular trends in semen quality, with some reporting a downward trend and others no change. However, evidence has eme rged of striking regional differences in semen quality, whether due to ethn ic, genetic, environmental, or lifestyle factors remains to be determined.