Media Sensationalizes Small Penis Study, Upsetting Patients

Fran Lowry

October 16, 2018

A study on penis length and infertility — presented as a poster at the American Society for Reproductive Medicine (ASRM) 2018 Scientific Congress in Denver — was picked up by media around the world, garnering an avalanche of reporting that distorted and misrepresented the results.

Exaggerated headlines went viral:

  • Willy Size Baby Link: Men Are Less Likely to Have Children if They Have a Small Penis

  • Study Has Shown Blokes With a Small Willy Are Less Likely to Become Dads

Stories misled:

  • Men With Small Penises More Likely to Be Infertile, Study Finds

Other updates were nonsensical:

  • Men With Small Penises More Exposed to Infertility

"I never spoke to any of the people who wrote these articles," said lead author Austen Slade, MD, from the University of Utah in Salt Lake City.

"Headlines such as 'men with short penises can't father children' are just plain wrong," he told Medscape Medical News. "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 said.

Headlines such as 'men with short penises can't father children' are just plain wrong.

Slade and his colleagues performed a retrospective review of all males 18 to 59 years of age who presented to the Men's Health Clinic at the University of Utah from 2014 to 2017.

Measurement of penile length became a standard part of the examination of all patients presenting to the clinic in 2014.

"We used stretched penile length, which is a surrogate for erect length, because there are obvious complications to trying to get an actual erect length," Slade explained. "We measured from the bone, the pubic symphysis, to the tip of the penis."

Of the 815 men in the review, 219 were infertile.

The mean stretched penile length in the infertile group was 12.5 cm; in the noninfertile group, it was 13.4 cm.

"There was a statistically significant difference between the patients who were coming for an infertility workup and all other patients," said Slade.

"It was surprising that there was this difference. I honestly wasn't expecting it. But even though it was only a 1 cm difference, it was statistically significant, with a P value of less than .001," he told Medscape Medical News.

But "I don't want to send the wrong message. It's discouraging enough, if you are going through an infertility workup, to be told that a short penis could be to blame," he pointed out.

Blaming Men

"I want to emphasize that it is not the size but rather a sign of an underlying endocrine or other disorder," Slade explained.

"There are plenty of men who have below-average length who have normal fertility and men with above-average length who have infertility. It's not necessarily something that people with shorter length need to be concerned about," he added.

Most reporters did not contact Slade to ask about his study, despite the fact that his contact information was listed on the poster.

"I found it surprising that I've only had two other people reach out to me, yet there are dozens of random articles out there quoting me. I think they must be taking quotes from other sources. Maybe it's the same person who writes for a number of different sources," he said.

"In general, differences in terms of sexual function are not really good predictors of men's fertility," said ASRM incoming president, Peter Schlegel, MD, from the New York Presbyterian/Weill Cornell Medical Center in New York City.

"There is a lot of confusion, obviously, between sexual function and fertility function. Only in very rare cases does sexual function actually affect fertility for a man," Schlegel told Medscape Medical News.

Sexual vs Fertility Function

"Talking about penises is a little bit distracting in terms about what is really important, and probably adds more confusion than benefit in terms of how we look at male fertility or infertility," he added.

"If you used other measures that correlate with testosterone, like anogenital distance, then you'll see a very similar relationship — in fact a much tighter relationship — between anogenital distance and testicular function and fertility," he explained.

Emily Barrett, PhD, from Rutgers School of Public Health in Piscataway, New Jersey, researches male fertility from the other end of the life spectrum.

"We work with newborn males. Dr Slade is working with adults, but it's all part of a developmental pathway. His work certainly needs some replication, and I would love to see the full paper because it's hard to tell from the abstract all of the details of the work," Barrett told Medscape Medical News.

Talking about penises is a little bit distracting in terms about what is really important.

"My sense is if this really is a true association, if there is something going on as this study suggests, that it's something happening much earlier in the development that is connecting penile length and fertility," she said.

"A lot of our work is on environmental chemicals we encounter every day," Barrett explained. "The ones I've worked on the most are called phthalates, which are in plastic. We all have measurable levels of them in our body and we know that these chemicals interfere with androgen production and testosterone. We have linked concentrations of these hormones in moms during pregnancy to changes in their sons' reproductive system."

Barrett and her group of researchers use anogenital distance, the distance from the anus to the genitals, to measure penis size.

"We know from animal models that anogenital distance is a pretty good approximation of what the hormonal environment is like during gestation. We are seeing that women with high amounts of these chemicals in their bodies have sons with shorter anogenital distance, and that's a sign of less masculine development," Barrett said.

"Dr Slade's study used stretched penile length, but we look at penile widths in our studies of babies because we haven't had a lot of luck measuring penile length. It's just harder to do consistently," she added.

"I agree with Dr Slade — one hundred percent — that size is not something men should be worried about. We are not saying that if your penis is shorter you are going to be infertile. Our work is really trying to help us understand why some men might be infertile. Tying these together speaks to the fact that there might be things that are going on in development that affect penis size," she said.

This study has received an inordinate amount of sensational media coverage, but "anything with the word 'penis' is like a magnet for reporters," Barrett said.

Slade, Schlegel, and Barrett have disclosed no relevant financial relationships.

American Society for Reproductive Medicine (ASRM) 2018 Scientific Congress: Abstract P-127. Presented October 9, 2018.

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