(CBS) In the tale of the tape, size might matter after all when it come to male fertility. Just not the size you think.
Scientists took a look at the distance from the anus to the scrotum of 126 men and tested how it related to fertility. Don't ask why they did this or why someone gave them a pile of money to figure it out. The important news is that they discovered that the size of that nether zone relates to semen volume and sperm count - and a bigger distance is definitely better.
The area is technically called the anogenital distance, or AGD, and researchers found that men whose AGD was shorter than about two inches had seven times the chance of being sub-fertile. That means a sperm count of less than 20 million per milliliter of semen, and it significantly reduces one's chance of impregnating a mate.
Researchers suggested that the hormone "environment" a fetus is exposed to in the uterus affects both sperm count and AGD. The study didn't speculate as to what might be affecting male hormones in the womb. But earlier studies, according to Reuters, pointed to a connection between a group of chemicals called phthalates and short AGD length in toddlers. Phthalates are often found in shampoos, paints, pesticides and plastics - including some plastic toys.
Last year, study author Shanna Swan of the University of Rochester Medical Center, appeared on "60 Minutes" (see video below) to explain the phthalates controversy. Swan's previous research found a relationship between exposure to phthalates and less masculine children. Some of the chemicals are already banned in toys in Europe.
So what's a guy to do if he's worried that he doesn't measure up? Get out the ruler, says Swan.
"It's non-invasive and anybody can do it, and it's not sensitive to the kinds of things that sperm count is sensitive to, like stress or whether you have a cold or whether it's hot out," she told Reuters. Then, of course, consult with your doctor.
The study is published in Environmental Health Perspectives.