There are many factors that go into fertility, for both men and women. Some research suggests that as many men face a fertility problem as do women. While sometimes a man’s fertility problem can be readily identified, in other cases it can’t.

As it turns out, there is something on a man you can measure that can indicate just how fertile he is.

Now, before you giggle, we’re not talking about the obvious measurement here. According to some new research, it may be possible to judge a man’s fertility by measuring the distance from his scrotum to his anus, something known as the “anogenital distance.” It’s believed that anogenital distance is shorter for men who may have abnormal testicular development, or testicular dysfunction.

It’s not just one study that’s shedding this new light on men’s measurements, either. Multiple studies at the Baylor College of Medicine, as well as another study at the University of Rochester seem to suggest a connection.

The University of Rochester study suggests that men who have a shorter anogenital distance have lower sperm counts, sperm that’s lower quality, sperm with lower motility, and sperm in lower concentrations.

Now, lest you think that these studies aren’t looking at all of the available measurements, you should know that the most recent study at Baylor also measured penis length, as well as anogenital distance. Men who were struggling with fertility did also show a shorter penis length.

That said, the stronger indicator was definitely anogenital distance. That is to say that penis length is a less reliable measurement of fertility than anogenital distance.

Of course, this doesn’t mean that, just because you and your partner have been trying to get pregnant for three or four months, it’s time to get out the tape measure. While these studies seem to be pretty convincing, it’s too early to really use this measurement as a diagnostic tool, even in the clinical setting.  According to researchers, there is a long way to go before fertility doctors will be able to use measurements of anogenital distance as a reliable predictor for fertility.