While the burden of undergoing fertility treatment typically has fallen on women, there's growing recognition of infertility in men — especially as people are putting off having kids until later in life.

Why it matters: Emerging data suggests that the count and quality of sperm decreases with age and can be impacted by other health factors.

• But researchers are still trying to understand at what age men are more likely to face fertility issues, making it more difficult to know when they should consider seeking treatment.
• "There should be more attention paid to advanced paternal age," says Robert Brannigan, vice president of the American Society for Reproductive Medicine.

Context: Age 35 and older is considered advanced maternal age in women, when it can be harder to conceive. But there's a "lack of consensus" in scientific literature about what constitutes advanced paternal age for men, Brannigan tells Axios. It's sometimes described as greater than 40 or 45, he says.

• As paternal age increases, there's greater risk of perinatal health issues including genetic diseases and neurodevelopmental concerns.
• That shouldn't discourage older hopeful dads from trying to conceive, he says, but it's a reminder to consider family planning early.

Between the lines: The overall decline in fertility rates as men age isn't as pronounced as it is in women, because of a "big difference" in biology, Brannigan says.

• Although women are born with all of the eggs they'll use in life, men continuously make new sperm.

In addition to age, sperm production could be adversely impacted by several factors. Among them:

• Extreme heat exposure, like from a hot tub. (However, cycling is "generally safe.")
• Drinking more than three alcoholic beverages a day, or using tobacco, marijuana or cocaine.
• Consuming food or drinks high in sugar content, which can potentially lead to low testosterone, which reduces sperm counts.

Zoom in: Certain lifestyle changes could make it possible to slowly improve sperm count and quality over time, Brannigan says.

• For example, Brannigan had a patient who stopped drinking and smoking, lost 40 pounds, and improved his sperm count over the course of six months. But "not everybody gets that response," he says.

If you're a man of any age who's interested in having kids in the future, "the best thing to do is get a baseline semen analysis," Brannigan says.

• Although men have historically been reluctant to get screenings to detect potential fertility issues, he says more younger men are now open to it.

What they're saying: "Although I don't plan on conceiving and having kids right now, this would be a great opportunity to find out if everything down there is just, you know, working properly," Patrick Pearson, a 28-year-old who works in finance in New York City, tells Axios about his decision to get a semen analysis.

• Pearson considers this one of several physical health metrics that he and his younger friends are much more interested in — like tracking their sleep — compared with their older friends. And it helped that the semen analysis Pearson conducted didn't require him to go into a doctor's office.
• The at-home screening "is taking the stigma out of male fertility," he says.

Go deeper: Tech firms court growing demand for male fertility services