‘No Cause for Panic’ as Sperm Counts Found To Be Steady

Several high-profile papers had suggested that sperm counts have drastically fallen globally over the past few decades. In contrast, the new data suggests that’s not the case, at least among men in the United States without known infertility.

“We found that at least in men with no known fertility challenges, sperm counts are largely stable and haven't changed significantly in the last few years, which is reassuring news. It doesn't necessarily mean that sperm counts among infertile men aren't worsening, but it does mean that for the average man, there's no cause for panic,” says lead investigator Scott D. Lundy, MD, PhD, Urology Program Director at Cleveland Clinic.

A closer look at the data

Dr. Lundy, along with colleagues from two other institutions, performed a systematic review and meta-analysis of studies published between 1970 and 2023, of U.S. men without known infertility, confirmed or not. A total of 58 articles met inclusion criteria, representing 75 unique studies of sperm concentration estimates in a total of 11,787 men. Of the 75 estimates, 51 were of populations of men with unknown fertility status, while the other 24 were of men confirmed to be fertile.

No changes in sperm concentrations were seen across the study populations over the 53-year period (P = 0.42), with similar results after adjustment for U.S. census region.

Some cause for reassurance

This was somewhat surprising, Dr. Lundy says. “We expected to find a subtle decrease over time, not a drastic decrease. I think finding nothing at all was a little bit surprising, and it certainly does not mean that we can ignore this issue or not study this further. But in this case, I think there's at least some evidence to suggest that we can be somewhat reassured.”

There was a slight decline, of -0.35million/mL per year, after adjustment for both census region and fertility status (P=0.04). However, among the 49 studies that reported sufficient data to determine total mean sperm count, there was actually a significant increase of 2.9 million per year between 1970 and 2018 (P = 0.03).

And, when stratified by fertility status, there were no significant changes in sperm count among the fertile men (P = 0.26) or those with unknown fertility status (P=0.06).

“There was a very modest decline when we did an aggressive correction, but I think in the grand scheme of this study where no other factors were significant, I'm less inclined to put a great deal of weight in that. And in fact, the mean concentration increased before the before the correction was applied, which suggests to me that this is likely a statistical anomaly, or at least certainly not a catastrophic decline,” Dr. Lundy says.

This study does not address whether infertility is on the rise. “We didn't track men who were fertile who became infertile. I think based upon the literature so far, that might be the case due to obesity or environmental exposures, and more research is needed to definitively answer that question. But in our population here, despite prior reports to that that received a great deal of press and concern, there is some cause for reassurance.”