Given the countless media depictions of the female "biological clock," you might assume that it's a gender-specific phenomenon.

But you'd be wrong.

As it turns out, it gets harder for both genders to have children as they age, and it also becomes more likely that children will have birth complications if they're born to older parents. The main difference is that the fertility rate drops off for men about five years later (at 40) than women, on average.

That's according to a 2007 study that followed about 2,000 couples in France. Another study found that men over 35 are twice as likely to be infertile compared to men 25 or younger, The Washington Post reported. What's more, the quality of men's sperm degrades as they age, raising the risk of miscarriages and making it more probable that the child will have health conditions such as autism.

Yet when we talk about "biological clocks" in terms of reproduction, society seems to emphasize the woman's age. Where does that come from?

Dr. Alexander Pastuszak, a urologist who specializes in male reproductive and sexual dysfunction at Baylor College of Medicine, told ATTN: that the misconception has to do with the fact that research on male fertility has only recently been publicized.

"Females have very distinct periods of reproduction, and those have a very clear beginning and end," Pastuszak said. "We know that men produce sperm from puberty through death largely, and until recently we did not have a good idea as to whether those sperm would be truly effective in initiating pregnancies throughout the lifetime.

"When you think about advanced maternal age, you start thinking about it at 35. In men, we're only really starting to think about it now, based on the data, at age 40 or 45."

What gets less attention is the fact that men's sperm count gradually reduces and the quality degrades after they turn 35, Pastuszak said.

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"The key is that, while women are born with a finite number of eggs, men form new sperm throughout their lives, with the existing sperm replicating its DNA and then splitting into two, over and over again," The Washington Post reported. "That might seem like a fountain of youth for men, but it’s actually more like a game of telephone — each time the process is repeated, there’s the chance that the DNA will change a little."