How a man’s fertility changes over time

Do men have biological clocks?

Not necessarily, but their fertility does change as they age, said Dr. Carolina Jorgez, assistant professor in the Scott Department of Urology at Baylor College of Medicine.

“There is a misconception that men’s fertility lasts forever,” Jorgez said. “But there is andropause – a gradual process in which the quality and quantity of men sperm decreases.”

During andropause, there’s a decline in testosterone levels and a man’s testicular tissue can deteriorate, she added. Men can experience andropause when they enter their 40s. According to the National Institutes of Health, andropause symptoms can include loss of libido and erectile dysfunction.

As men get older, their sperm also ages and can introduce single mutations to an embryo, said Dr. Thomas Garcia, assistant professor in the Scott Department of Urology. But that doesn’t mean the mutation is automatically dangerous to the embryo.

“Most genes have two copies, and if there’s a damaging mutation on one copy, it’s not that bad,” Garcia said. “You need both copies of the gene to lose function. For most mutations, it’s needs to be both (copies).”

High fevers and other physiological problems can affect a man’s fertility, but the sperm may not change until three months later. More than 10 percent of American men are infertile, Garcia said. Causes range from obstruction, cryptorchidism, low sperm counts and lower testosterone levels.

Testing for infertility in men is simpler than the process is for women, Jorgez said. The initial testing includes semen analysis to determine the quantity and quality of the sperm and hormonal analysis. In cases where there is no sperm in the semen, doctors will conduct a testicular sperm extraction, a surgical procedure where tissue is removed from a part of a testicle to try to find sperm that can be used in assisted reproductive technology, she said.

Unlike women who typically start experiencing lower fertility when they turn 35, most men can father children well into their elder years.

Dr. Michael Eisenberg, a urologist and male fertility specialist at Stanford Medicine, is a former fellow in Baylor’s urology department. In 2017, Eisenberg co-authored several papers on the rising age of fathers in the U.S.

Advanced paternal age is associated with negative effects on both mothers and babies, Jorgez said. Higher paternal age, which is considered over the age of 45, is associated with an increased risk of premature birth, low birth weight, gestational diabetes and early-onset cancer and neuropsychiatric disease in babies.

Although it’s known that advanced paternal age can be associated with disease, neonatal screenings are not as common as when the mother is older, she said.

“Paternal age is rising within the U.S. among all regions, races and education levels,” according to the paper. “Given the implications for offspring health and demographic patterns, further research on this trend is warranted.”

Jorgez believes the conversation surrounding older first-time fathers is cultural rather than biological, as it can be with older first-time mothers. She referenced Eisenberg’s work as an example.

“Sometimes men in their 60s will have a child with a woman in her 30s,” Jorgez said. “When the child is in college, maybe their father has passed or they’re very elderly, so they cannot concentrate in college because they’re worried about their older parent.”

Learn about Lester and Sue Smith Urology Clinic at Baylor Medicine. 

By Julie Garcia

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