Declining sperm count and fertility in males: an epidemiological controversy

There have been several suggestions from different populations that sperm count has decreased in the past 20 years. Concerns have, however, been raised in the interpretation of these findings, particularly with regards to subject selection mechanisms and data-analysis. Furthermore, these findings are inconsistent with the reports that male infertility rates have remained constant during the past 3 decades. The increased number of men seeking consultation on infertility may only be the result of the tendency of couples to delay pregnancy and the increased availability of treatment. Moreover, sperm concentration is not always in itself the determinant of male fertility, so the use of sperm count as an indicator of male infertility in epidemiological studies should be considered with caution.