Where Has All the Sperm Gone?

In the most comprehensive study to date, researchers have found a 50% decline in the average sperm counts among men in North America, Europe, New Zealand, and Australia.

Fifty percent seems like a lot—and it is. And there’s no sign the decline is slowing, which means that male infertility could become a more common problem in the future. The percentage of patients whose sperm counts are between 0-5 million per milliliter (M/mL) increased from 9 percent to more than 12 percent in the last ten years. Anything below 15 M/mL is “low.”

Many of the studies performed on this subject have been done in men who are sperm donors. Donors are considered already to have high counts. This leads scientists to believe that these trends may be further magnified in the general population.

What happened to all the sperm?

Men today are producing less semen than fifty years ago and that semen has fewer sperm cells in it. The explanations outlined by researchers seem endless: pesticides, obesity, smoking, lead, x-rays, stress, diet, lifestyle changes, the environment, alcohol, endocrine changes, fetal exposure to chemicals, etc.

Because sperm count is the best measure of male fertility, the changes are alarming. However, many couples could avoid the problems they encounter when they attempt to get pregnant  if they started trying to conceive just a few years earlier. Recently, both the average age of marriage and the average age of first conception have both dramatically increased.

What are the implications of a fertility decline?

Low sperm counts are a signal that men’s health is heading in a negative direction. Poor sperm health is linked to cardiovascular issues, obesity, cancer and more generally to higher rates of hospitalization and death. While men’s life expectancy is increasing overall thanks to advances in medical care, nutrition and sanitation, it’s entirely possible that the life expectancy could start to drop again someday soon.


Cha, Ariana Eunjung. “Sperm Count Drops 50 Percent in U.S. and Other Parts of the World.” Chicagotribune.com, Chicago Tribune, 3 June 2018.

Fetters, Ashley. “Sperm Counts Continue to Fall.” The Atlantic, Atlantic Media Company, 12 Oct. 2018.

Sifferlin, Alexandra. “Men’s Sperm Counts Are Dropping Worldwide: Study.” Time, Time, 25 July 2017.

Stein, Rob. “Sperm Counts Plummet In Western Men, Study Finds.” NPR, NPR, 31 July 2017.