2023 Rewind: Penis Size Has Increased Over 30 Years. So Why are Experts Concerned?

This piece is part of EDGE's 2023 Rewind series. We're reaching into our archives and sharing some of our favorite stories from the past year.

Why is the report that men's penis size has increased in the past 30 years so worrisome to experts?

"Studies of men from around the world show that the length of the erect penis has grown 24% over the last 30 years," reports USA Today.

While many would welcome the development, fertility experts are not.

"The million-dollar question is why this would occur," explained Dr. Michael Eisenberg, a urologist and male fertility specialist at Stanford Medicine, who led the research, published Tuesday in The World's Journal of Men's Health. The study is called "Is an increase in penile length cause for concern?".

Other research has shown that both sperm count and testosterone levels are falling.

Penile length may not be directly related to fertility, Eisenberg said, but anything that changes the reproductive system is fundamental to human existence and "something we should pay attention to and try to understand why."

The study came about when Eisenberg noticed trends in trends in male reproductive health data, including lower sperm quality and testosterone levels, and decided to explore if there were additional changes, such as to physical anatomy.

In the study :Eisenberg and his colleagues compiled data from 75 studies, conducted between 1942 and 2021, that reported on the penile length of 55,761 men. The team found that the average erect penis length increased by 24% over 29 years, a trend they saw around the world," USA Today writes.

Eisenberg said that the increase may be another indicator that environmental exposures -- such as environmental pollutants or increasing sedentary lifestyles -- are causing reproductive-related changes.

Eisenberg discussed the motivation for the study, the (potential) implications of the findings for men's health, and new opportunities to investigate the impact of external environmental factors on human health.

He and his colleagues initially expected a reduction in penile size. "We conducted a meta-analysis in which we examined all reports, to our knowledge, of penile length," he tells USA Today. "We looked at flaccid, stretched and erect length and created one large database of measurements. What we found was quite different from trends in other areas of male fertility and health. Erect penile length is getting longer, from an average of 4.8 inches to 6 inches, over the past 29 years."

Eisenberg continues that the changes are worrisome because they took place over a shorter period of time. "If we're seeing this fast of a change, it means that something powerful is happening to our bodies. We should try to confirm these findings and if confirmed, we must determine the cause of these changes."

He continued: "There could be a number of factors at play, such as chemical exposure, like pesticides or hygiene products, interacting with our hormonal systems. These endocrine-disrupting chemicals -- there are many -- exist in our environment and our diet. As we change our body's constitution that also affects our hormonal milieu. Chemical exposure has also been posited as a cause for boys and girls going into puberty earlier, which can affect genital development."