Are Sperm Counts Falling?

CBS News interviewed me this week and wondered whether men’s sperm counts are on the decline. Since journalists pose this question to me regularly, it seems like a good idea to discuss why this notion has persisted and whether it has any merit.

The Issue of Falling Sperm Counts

In the mid-1990s, a published study suggested that the average sperm counts of healthy men had fallen over the past 50 years. This started the 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 developing 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 . This is called selection bias
• Semen analysis methodology has changedover time and could have influenced the findings. This is called method bias.
• 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. This is a form of analytical bias.
• There are regional, continental, and seasonal differences in sperm countsaround 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 U.S. This is called population bias.

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, taking 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.

Should We Hit the Panic Button?

Sure, there are studies that show sperm counts decreasing over decades, pointing fingers at everything from environmental toxins to our modern couch-potato lifestyle. It’s a complex problem with a myriad of reasons without a  doubt.

But here’s the kicker: a lower sperm count doesn’t equate to infertility. Many men with less-than-ideal counts are still crossing the finish line  and winning the baby prize. And remember, science is our helping hand. Reproductive technologies are now offering solutions that were the stuff of sci-fi a decade ago.

So, before we  claim a spermapocalypse, let’s focus on what we can do: pay attention to advancing medical science and pursue healthier lifestyle choices that can shore up sperm quality. Panicking? No. Paying attention? Absolutely.