Decline in human sperm counts during the past 50 years?

Abstract

There is widespread concern that environmental pollutants acting as xenoestrogens may affect human fertility adversely. Whether this has already made an impact on human fertility worldwide remains debatable at the present stage. Ever since Carlsen's analysis reported that sperm concentrations have decreased over the last 50 years there has been renewed attention and curiosity amongst peer groups in different parts of the world. Though Carlsen's mode of data analysis was criticized on many fronts, a number of similar studies that appeared subsequently have contradicted each other. The article has reviewed the literature to determine whether semen counts have indeed changed in the past 50 years. We conclude that sperm counts vary enormously between different countries or regions of the world and also between individual men. There is even marked variation between counts on the same men. It is therefore not surprising that not all analyses of sperm counts find the same patterns. We suggest that a well 颅designed prospective study should be performed in several different regions of the world in order to extrapolate the results on sperm counts and to evaluate the potential effect of external factors on male reproductive health. It is hoped that the conclusions from these new studies might put an end to the controversy that surrounds this issue.