Are Sperm Counts Falling?

Posted on by Paul Turek, MD

They asked me again. It never seems to end. CBS News interviewed me this week and wondered whether men’s

The Issue of Falling Sperm Counts

In the mid 1990s, a paper was published that suggested that the average sperm counts of healthy men had fallen over the past 50 years. This started the whole debate on this issue. The paper reviewed the findings from various studies done from 1938-1991 and found a decrease in sperm counts over time. Importantly, the data from the early part of this period was primarily from New York, while the later data was from Europe, with a large portion from Third World countries. They concluded that sperm counts had fallen over the past 50 years around the world. This paper, combined with the fact that the World Health Organization has lowered what is considered to be a “low” sperm count from 60 million sperm/mL to 15 million sperm/mL over the last two decades, has generated significant worldwide concern.

My Take on the Falling Sperm Count Issue

Knowing science the way I do, there may be some statistical “sleight of hand” going on here. Here’s why:

  • Sperm count data was “clustered” geographically in the paper which influences things. For example, if the New York data are excluded, there is no decline in sperm counts over a half century.
  • Semen analysis methodology has changed over time and could have influenced the findings.
  • The statistical methods used to analyze the “bar bell data” (two lumps of findings at either end with nothing in between) are too simplistic for the problem.
  • There are regional, continental and seasonal differences in sperm counts around the world. To the delight of New Yorkers, a subsequent study showed that their sperm counts are about 50% higher than those of men in Los Angeles. This really started the battle of the biggest Kahunas in the US.

Technically, then, the scientific argument that sperm counts are falling can be poked at and prodded to the point of becoming simply interesting cocktail conversation. Still, in the back of my mind, it occurs to me that just because it is not proven to be true doesn’t mean that it is not true.

So What’s A Guy to Do?

In this recent interview, I did cite my concern that the lifestyles of many men expose them to all sorts of sperm damaging activities such as hot tubs and baths, laptops on laps, recreational drugs, various hair-preserving medications and unrelieved stress. And I mentioned for the umpteenth time that men should treat their bodies like temples, and take all things in moderation if they want to conceive. Finally, bringing in one of my favorite analogies, I emphasized that sperm production loves to run hard like an engine, but it can also be detuned by poor lifestyle choices. I also stated something during the interview that didn’t make the cut on CBS television this time (but did in the past): that maybe women are simply more fertile than they were 50 years ago and that men are fully the men that their grandfathers were.