The finding, published in the journal Fertility and Sterility, suggests that men who have fertility problems should have a broader check-up as well.
It’s not clear if some lifestyle or environmental factor might be hurting both a man’s overall health and his sperm products. But it’s very likely the problem is genetic, said Dr. Michael Eisenberg, an assistant professor of urology and director of male reproductive medicine and surgery at Stanford University, who led the study.
“About 15 percent of all couples have fertility issues, and in half of those cases the male partner has semen deficiencies,” Eisenberg said in a statement.
“We should be paying more attention to these millions of men. Infertility is a warning: Problems with reproduction may mean problems with overall health.”
Health worsens as men get older. “But here, we’re already spotting signs of trouble in young men in their 30s,” Eisenberg said.
The team studied more than 9,000 men who gave several semen samples during treatment at fertility clinics. About half the men had something wrong with their sperm or semen. Most were young men, as they were starting families, most with no obvious health problems.
But 44 percent of the men did have other health problems. Men who had high blood pressure or artery disease or who had suffered strokes all had higher-than-normal rates of semen abnormalities.
“For example, 56 percent of men without hypertensive disease had normal semen quality, but only 45 percent of men with hypertension had normal semen quality,” Eisenberg’s team wrote.
“A man’s health is strongly correlated with his semen quality,” Eisenberg said. “Given the high incidence of infertility, we need to take a broader view. As we treat men’s infertility, we should also assess their overall health.”
There are good odds that genes are involved, Eisenberg said.
“As approximately 15 percent of the male human genome is involved in reproduction, it is conceivable that other health ailments may also be linked to defects in fertility,” he added.
That doesn’t necessarily mean an inherited problem, although it could. Smoking, excessive drinking and poor diet can also damage DNA. And some studies suggest men who don’t get enough sleep can hurt their fertility while others link poor semen quality to exposure to some chemicals.