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

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

When it comes to fertility, the focus tends to fall on women and their (noisy) biological clocks. Yet it’s not just women who have to consider age when considering having children. Experts agree that 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 have to deal with changes in egg quantity and quality from 35 years old.

“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, men over the age of 45 are much more likely to have children than four decades ago, yet few men recognize that their biological clocks are also ticking.”

A 2017 study from Beth Israel Deaconess Medical Center and Harvard Medical School looked at IVF patients and found that while women between the ages of 40 and 42 had the most difficulty conceiving, the chances of a live birth decreased among women. older men – even those whose partners were younger women. Exactly why this is, however, remains to be researched.

Dr. T. Mike Hsieh, director of the UCSD Men’s Health Center and professor of urology, told Yahoo Life that while there’s “not as much data” on male fertility as there is for women, there is clear that “increasing paternal age is associated with decline in sperm count, sperm quality, sperm volume, testosterone, and capacity for sexual activity or erectile dysfunction. There is no “specific threshold”, which is generally accepted as advanced paternal age begins at around 45 years old.

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

“This means that when the DNA payload is delivered to the egg at fertilization, it is split into single strands, rather than entirely, into double strands,” Turek explains. DNA soon after fertilization, but if the load of damage exceeds the ability of the egg to repair it, there will be no pregnancy or possibly miscarriage – another case, on a biological level, of women cleaning up the damage that men make.

Frederick also points out that “the risk of developing a medical condition or being exposed to environmental toxins increases with age for men”, which can make them less fertile.

“A history of chronic disease, such as sickle cell disease, chronic kidney disease, liver conditions 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 negatively affect sperm function.”

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

“Dropping testosterone levels in men can lead to decreased sex drive, erection problems, and difficulty achieving ejaculation — all contributing to the couple’s infertility,” Frederick says. “The level of testosterone appears to influence sexual function and desire in a man, and testosterone replacement improves erectile function, but also causes lower sperm production and leads to infertility.

Ultimately, however, Frederick notes that this area still has a long way to go. “Many unknowns remain with regard to the elderly man and infertility,” she says. “Further research will allow us to better understand age and its impact on all areas of male infertility.”

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