A review of male fertility data recently published in a national medical journal has found that human sperm counts are in a long-term decline. Among a subset of men who had not yet fathered children, sperm counts decreased roughly 50 percent between 1973 and 2013.

The results led Frederick vom Saal,  Curators' Distinguished Professor Emeritus of Biological Sciences at the University of Missouri, who was not involved in the study, to conclude that "we are in a death spiral of infertility in men."

Is the situation really that dire? For perspective, we spoke to Puneet Masson, a urologist and the University of Pennsylvania's director of male reproductive medicine and surgery.

What is your take on the study of decreasing sperm counts? 

The article presents some compelling data.  But these are just population studies. I think the question that needs to be asked is: Is this decline a clinically significant decline?  Even though sperm count may be declining, people are still getting pregnant. And I think we need a better study to do that. Also, will the decline continue, or will it plateau? We don't know.

Normal sperm count is anything greater than 15 million sperm per milliliter of ejaculate. That's a lot. The article talked about how the number has declined to 47 million.  That's still in the normal range.

That being said, anecdotally, a lot of us that do male fertility evaluations are seeing a greater percentage of environmental or lifestyle issues that can affect sperm development.

For instance, we are seeing a tremendous increase in patients that are obese. We know that obesity is becoming more and more of a problem in the overall population. Rising estrogen levels go hand in hand with obesity. Also, with obesity, there could be warming of the scrotal area, which could affect sperm counts. A man's testicles have to be two degrees Centigrade cooler than the rest of his body to create an ideal environment for sperm development.

A second article, published at about the same time, suggested that exposure early in life to environmental estrogens – in mice, at least – leads to lower sperm counts. What about that?

Puneet Masson, a urologist and the University of Pennsylvania’s director of male reproductive medicine and surgery.
Penn Medicine
Puneet Masson, a urologist and the University of Pennsylvania’s director of male reproductive medicine and surgery.

I'm glad something like this article came out because it highlights the importance of environmental health. But are lower sperm counts related to external toxins? Could it be exposure to endocrine-disrupting compounds? Are there more hormones in food? Or is it driven by lifestyle changes of people over time that can lead to substandard health? Is it because we're eating unhealthy and not exercising as much as we should be, and our body has a lot more fat? The authors never really spell it out.

This was an animal study. In humans, there is an enzyme in our bodies that converts testosterone to estrogen. Fat cells have a lot of the enzyme. If someone has more fat tissue, there's a concern they may have excessive conversion of testosterone to estrogen. When a man's estrogen level goes up, those higher levels, in effect, may tell the body to decrease its ability to make sperm. That's basically what the authors are driving at. We're all concerned about rising estrogen levels.

When should a man get a fertility evaluation? 

It should be done after a year of trying to get a woman pregnant, or if there is a concern for a male factor issue, such as if the man is told he has genetic or developmental risk factors. If there's a concern about sexual functioning. If there are concerns about a physical exam finding or reproductive surgery the male may have had.

We see people coming in all the time for a male fertility evaluation simply because they're curious. In Philadelphia, there's a highly professional patient population that likes to plan and be ahead of things. We see that in many large cities. So I see at least one person a day who is not infertile. I'll ask how long they've been trying. And they'll say something like nine days.

Infertility can be due to a number of reasons other than an underlying issue with sperm. One notable reason, in the top five, has to do with intimacy or sexual function. Or decreased libido. This may lead to diagnoses of other things, such as erectile dysfunction or hypergonadism. We also see people who are having difficulty conceiving because they are not having sexual relations. Their jobs may require them to travel frequently, for instance.

Are there any new ways to treat male infertility?

There are numerous ways to treat it. It depends on the underlying cause. In some men, if there's a hormonal imbalance, they can go on medications. If there's an anatomical issue, they might benefit from surgery. For other men, there may be lifestyle changes. If someone has high heat exposure as part of his job, he can try to minimize that to keep his testicles cooler.

Low sperm count is a gateway for addressing other issues. As a population in the U.S, we have become larger and unhealthier. What we are trying to encourage, as a nation, is to have people take control of their overall health, and being aware of risk factors — environmental things — so they can make decisions or changes to lead to overall better health.

Much of the patient population we are seeing is guys between 20 and 45 that may not have had the best follow-up with their primary doctor. Many times, the male fertility doctor is the one that's encouraging greater lifestyle changes that are important for their overall health. In our clinic, we have a fertility nutritionist. Anyone that has a Body Mass Index of more than 30, I encourage them to exercise, eat healthier, and lose weight.

What can parents do to protect their sons' fertility? What should men do? 

For parents of young boys, it's important to stay on top of their appointments with their pediatrician, just to make sure their son is developing appropriately during puberty. If there is any concern, there could be an endocrine evaluation. For instance, Klinefelter syndrome, which affects one in every 500 males, can lead to infertility. We're detecting more and more of that at puberty rather than later during fertility exams. The one thing all Klinefelter men have in common is that there is no increase in testicular size. And in puberty, that's the first thing that grows.

Also, parents should instill good life lessons. If the parents are morbidly obese, children take note of that.

Grown men should do self-testicular exams, have regular follow-ups with a primary health-care provider, and stay healthy.