The Measure of a Man's Private Parts Is Connected to His Fertility

By Patrick Morgan | April 4, 2011 4:11 pm

When it comes to male fertility, length matters—the length between the scrotum and anus, that is. New research suggests that measuring a man’s “anogenital distance,” or AGD,  is a fast, low-tech, relatively accurate method of getting an idea of the quality of a man’s sperm.

In a new study, University of Rochester professor Shanna Swan and her colleagues broke out the measuring tape and assessed the anus-to-scrotum distance of 126 men born in 1988 or later. The men whose AGD’s were shorter than the average of two inches were 7.3 times more likely to have low sperm counts than their more well-endowed…er, well-distanced, brethren. These men with shorter AGD’s also had low sperm motility and poor sperm morphology.

So why on Earth, you’re wondering, would this be the case?

As DISCOVER said in the 2008 article The Dirty Truth About Plastics, “Biologists recognize a reduction in the length between the anus and the sex organ as an external marker of feminization, easily measured because it is typically twice as long in males as in females.” This reduction in AGD “may be caused by exposure to endocrine-disrupting chemicals” in the womb; Swan’s previous research specifically implicated prenatal exposure to phthalates, a commonly-used chemical in plastics, shampoos, paints, and pesticides.

Noting that nearly a fourth of the men in the study had low sperm counts, Swan urges young men to whip out the rulers and measure themselves. “It’s non-invasive and anybody can do it,” she says. We’re willing to bet she’s at least half right.

Related Content:
DISCOVER: The Dirty Truth About Plastics
Discoblog: Vatican Science: Pope Blames Male Infertility on…the Pill
Discoblog: Warning All Competitive Male Cyclists: Less than 5% of Your Sperm May Be Normal
80beats: Older Fathers’ Sperm May Produce Children With Slightly Lower IQs
80beats: Men Have a Biological Clock, Too

Image: flickr / The Welsh Poppy

  • Matt B.

    “Swan urges young men to whip out the rulers and measure themselves.”

    So what distance are we hoping for?

  • WonkoTheSane

    “Anogenital distance”? Just call it the taint.

  • megan

    And what are the men to do about it? If anything it can help explain troubles in a couple’s fertility. But like most things I bet making sure his testicles stay cool as a having receded pair situated back near between thighs due to their position closer to the anus, are kept too warm while also stuck in tight underwear briefs and jeans than allowed to be freeier, as they’re not sitting as far forward nor hang as freely away from the anal region. Boxers and cooling such during a couple’s attempts at pregnancy sounds natural.

  • John T

    Cooler testicles are better for sperm count. The reduced distance no doubt puts testicles into a warmer location that would reduce sperm count. You gotta think multidimensionally to figure stuff out. It doesn’t have anything to do with “feminization”, it’s all about temperature. That’s freakin’ obvious.

  • Matt B.

    Sorry, I missed the phrase “the average of two inches”.

  • NZNeep

    John T- yeah, I’m sure the scientists who have been studying this for years never thought of that, just as I’m sure the author of this 5 paragraph long article covered every single explanation they studied. You’re totally smarter, that’s freakin’ obvious.

  • Treykirk


    • Trey



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