Penis Size Unrelated to Fertility

Mar 10, 2019

Is it true that men with a smaller penis are more likely to be infertile?

The simple answer is no. A number of factors can contribute to infertility. A man can have a low sperm count, or his sperm might not be fully developed. He could have retrograde ejaculation, which causes semen (including sperm) to travel backward into the bladder instead of forward out of the penis when he ejaculates. Medications could affect his sperm production. But penis size is not a factor.

Last fall, however, some media outlets reported that men with small penises had lower odds of fathering children. Where did this notion come from? The news stemmed from a poster presentation at the 2018 Scientific Congress of the American Society for Reproductive Medicine in Denver.

Unfortunately, not all the facts were reported accruately. What happened? Let’s take a closer look.

The Study

Eight hundred fifteen men between the ages of 18 and 59 participated in the study, conducted by a research team from the University of Utah. Two hundred nineteen men were infertile; the remaining 596 men were not.

The researchers measured each man’s stretched penile length (SPL) – the distance from the pubic symphysis (a joint near the pubic bone, just above the penis) to the meatus (the urinary opening).

The infertile men’s average SPL was 12.5 centimeters (4.92 inches). The average SPL for the other men was 13.4 centimeters (5.28 inches).

The authors wrote the following conclusions:

This is the first study to demonstrate an association between a shorter SPL and infertility. It is unknown if reduced length is a result of genetic or congenital factors associated with infertility such as testicular dysgenesis syndrome or the result of underlying hormonal differences between the two groups. Further investigation is needed to better understand the association of shorter stretched penile length with male infertility.

The Media Coverage

Not long after the presentation, news outlets started sharing the news, sometimes with misleading headlines linking smaller penises directly to infertility.

But that’s not what the study found, lead author Dr. Austen Slade told Medscape Medical News, noting that he had not spoken to any of the reporters who wrote the misleading articles. (His contact information was included on the poster.)

“Headlines such as 'men with short penises can't father children' are just plain wrong," Dr. Slade said. "What we are saying here, and it would have been obvious if any of these reporters had contacted me, is that a shorter length may be an indication of something else going on."

"Fertility depends on many factors, but not on the size of a man's penis," he added.

As the abstract conclusion explains, penis size could be connected to hormonal, genetic, or congenital (present at birth) factors associated with infertility. The authors called for more research to better understand the study’s results.

Why were readers misled?

It’s possible that the news outlets saw the association between penis size and infertility but didn’t look beyond that for further explanation. Dr. Emily Barrett of Rutgers School of Public Health in New Jersey told Medscape, “anything with the word ‘penis’ is like a magnet for reporters.”

How can you know that health information is accurate?

Whether it’s a news piece or health information in general, there are steps you can take to make sure you’re getting accurate reporting.

  • Consider the source. Is it an outlet you’ve never heard of? Is it an organization you trust?
  • Check the date. How current is the information?
  • Look at how the information was gathered. Does it come from a respected medical journal? From scientists or healthcare providers? From patients?
  • Talk to your doctor. Don’t hesitate to show the article to a professional and ask questions.

See more tips for assessing health information (especially on the internet) here.


American Academy of Family Physicians

“Health Information on the Web: Finding Reliable Information”

(Last updated: January 4, 2018)

Fertility and Sterility

Slade, A., et al.

“Stretched penile length and infertility, a new association”

(Abstract presented at the 2018 Scientific Congress and Expo of the American Society for Reproductive Medicine. October 9, 2018)


“Pubic symphysis”

(Reviewed: March 19, 2015)

Medscape Medical News

Lowry, Fran

“Media Sensationalizes Small Penis Study, Upsetting Patients”

(October 16, 2018)

“The Internet and Sex Health Info”

Oaklander, Mandy

“Can You Really Trust the Health News You Read Online?”

(December 9, 2014)

Urology Care Foundation

“What is male infertility?”

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