Do men have biological clocks? Here’s how age affects fertility in men.

Do men have biological clocks? Here’s what experts say about male fertility. (Photo: Getty Image; Illustrated by Maayan Pearl)

When it comes to fertility, the focus often falls on women and their (loudly ticking) biological clocks. Yet it is not only women who should consider age when considering having children. Experts agree that so is male fertility depends on their age.

According to dr. Jane L. Frederick, a reproductive endocrinologist, women receive the most attention because they have a finite number of eggs at birth and suffer changes in egg quantity and quality from age 35.

“Women play an obvious role in reproduction, leading us to believe that the topics of fertility, pregnancy and childbirth are women’s issues, with no male involvement after they provide sperm,” she explains. “However, older men over the age of 45 are much more likely to have children than they were 40 years ago, and yet few men recognize that their biological clocks are also ticking.”

A 2017 study from Beth Israel Deaconess Medical Center and Harvard Medical School examined IVF patients and found that while women ages 40 to 42 had the most difficult time conceiving, the chances of having a live birth decreased in older men — even those whose partner was younger women. How exactly this happens, however, remains to be investigated.

Dr. T. Mike Hsieh, the director of UCSD Men’s Health Center and professor of urology, tells Yahoo Life that while there is “not as much data” on male fertility as there is on female fertility, it is clear that “increased paternal age is associated with decline in sperm count, semen quality, semen volume, testosterone, and ability for sexual activity or erectile dysfunction.Although there is no “specific cutoff”, what is commonly accepted as advanced paternal age begins around 45.

Dr. Paul Turek, a urologist and expert on male fertility, adds that men in their late 50s and 60s experience a “marked decline” in fertility compared to younger men. The cause of this decline, he says, may be not only the body’s biological clock, but also the fact that certain risk factors increase as men age. As he points out, “a body must be very healthy to be fertile normally.” He adds that the “quality of the DNA package” is “altered or diminished” as men age.

“That means when the DNA payload is delivered to the egg at the time of fertilization, it is broken into single strands, rather than intact, into double strands,” Turek explains. “Eggs try as hard as they can to ‘repair’ the DNA early after fertilization, but if the amount of damage exceeds the egg’s ability to repair it, there will be no pregnancy or possibly miscarriage – another case, on a biological level, of women cleaning up the mess men make.”

Frederick also points out that “men’s risk of developing a medical condition or exposure to environmental toxins increases with age,” potentially making them less fertile.

“A history of chronic disease, such as sickle cell anemia, chronic renal failure, liver disease such as cirrhosis, or malnutrition can have an effect on sperm production,” she notes. “Men who develop medical problems later in life may take medications that can adversely affect sperm function.”

Men’s testosterone levels steadily decline over time, which can also affect their ability to father a child.

“Falling testosterone levels in men can cause a decrease in sexual desire, erection problems, and difficulty achieving ejaculation — all contributing to couple infertility,” Frederick explains. “The level of testosterone seems to increase sexual function and desire in a man, and testosterone replacement improves erectile function, but also causes sperm production to decrease and leads to infertility.

In the end, however, Frederick notes that this field still has a long way to go. “There are still a lot of unknowns regarding the older man and infertility,” she says. “Further research will give us a better understanding of age and its impact on all areas of male infertility.”

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