Study finds no decline in sperm counts.

A recent French study showed a 20-year decline in Parisian men's sperm counts. That report, and others with similar results, raised the fear that an environmental toxin is delivering a crippling blow to male fertility (SN: 2/25/95, p. 127).

Now, two U.S. studies come to the opposite conclusion. They suggest no drop in sperm counts worldwide-and even a slight increase in the United States. "We were surprised," says Harry Fisch of Columbia-Presbyterian Medical Center, coauthor of the reports published in the May Fertility and Sterility. In one study, Fisch and his colleagues reviewed data from three sperm banks, one in New York City, one in Los Angeles, and one in Roseville, Minn. They analyzed information from men who had banked sperm from 1970 to 1994 before undergoing vasectomy, a sterilization procedure. The scientists found a slight, but significant, increase in sperm concentrations during the 25-year period. They report no change in semen volume or the sperms' ability to swim. The researchers also found a significant geographic variation in sperm counts. For unknown reasons, men who had banked sperm in New York had the highest sperm counts. These men averaged 131.5 million sperm per milliliter of semen, while men in Roseville logged in at 100.8, and men in Los Angeles had 72.7. In the second study, Fisch and his colleague Erik T. Goluboff, also at Columbia-Presbyterian, reanalyzed data from a 1992 metanalysis that combined a number of independent studies to reveal a worldwide decline in sperm quality. The earlier studies in this metanalysis were often conducted in New York City, whereas the later ones included more developing countries, where sperm counts tend to be low. After correcting for such geographic variations, Fisch and Goluboff found no sign of an overall global decline.