Sperm Counts Unchanged Over 50 Years

"Everything in our study indicates that the average man's sperm count is not changing," said study co-author Rebecca Sokol, M.D., of the Keck School of Medicine of USC. The results are published in the March issue of the journal Fertility and Sterility.

Sokol and her colleagues looked at semen samples collected from 1,385 men at LAC+USC Medical Center over a three-year period between 1994 and 1997. At the time samples were taken, the men were partners of women who were seeking infertility treatment.

Examining total sperm counts and semen abnormalities, the investigators found that of the half who showed some sperm abnormality, based on World Health Organization criteria, 52% had sperm that were borderline low in mortality; 18% had abnormal sperm concentration, and 14% had abnormally shaped sperm.

Previous studies popularized in the press claimed that male sperm counts were declining because of everything from pollution to sedentary jobs to tight underwear - and even spending too long in the car.

Sokol said this new study was both large and well designed, so that the results can be trusted to be an accurate reflection of sperm quality among American men. She noted that, coincidentally, the pool of men who provided semen samples primarily worked in blue-collar jobs that could have exposed them to significant environmental toxins - so if a drop was found and if pollutants were the cause, it would have been likely to be represented in the findings. Sokol and her colleagues nevertheless found that values for the average sperm count were identical to the count reported in the 1950s.