A healthy man produces between 60 and 100 million sperm every day. This number decreases with age while mutations increase, increasing the risk of health problems in the offspring.
Men are usually fertile into old age, but the biological clock continues to tick for them too and leaves its mark. For example, mutations in the genome are more likely, explains the andrologist and urologist Christian LeiberCaspers.
“Several studies have found that men in their 40s, 50s, or 60s have these changes.” He is head of the andrology department at the Maria Hilf Hospital in Krefeld. “Statistically, the risk of possible damage or malformations is greater in the offspring.”
The likelihood of mutations in sperm increases in men as they age. Since the entire genome is copied each time, there is a risk of minor or major errors that can multiply over the years. In addition, the body’s ability to automatically repair possible defects in the genetic makeup no longer works as well in older people.
If a 20 to 30yearold man passes on about 20 mutations to his son, by his 40s it would already be 60 mutations. In turn, the son of an older man will pass a variety of new genetic changes to his own son, who in turn will pass them on to his male offspring.
Females have a limited number of eggs
When a woman is born, she has a limited number of eggs, which decreases throughout her life. When they end, menopause comes. A man, on the other hand, is constantly producing new sperm.
“We estimate that a healthy young man has more than 39 million sperm in a semen sample. And there are men who ejaculate 200, 300 or even 400 million sperm at once.
An intensive selection takes place here, so that only the fittest gamete the most agile, best, most beautiful gets into the egg, all others fail. But even if around 90 percent of the sperm do not correspond to the ideal type and even have certain defects, this is not a problem from a biological point of view, says LeiberCaspers.
Late Fatherhood
The average age of mothers having their first child has continued to rise in Germany in recent years and, according to the Federal Statistical Office, was 30.2 years in 2020. Pregnancy over the age of 35 is already considered a high risk. For example, the child may develop trisomy 21, also known as Down syndrome. Men are also becoming fathers later and later, with an average age of 33.2 years.
In the last decade, research has focused on the workings of men’s biological clocks and the risks associated with late fatherhood. So far, however, this has not led to conclusive results or clear recommendations. Conducting such studies is complicated because the mother’s data must also be taken into account. And so the possible combinations are almost endless.
“It is difficult to say which individual factors could be decisive for a child’s health,” explains LeiberCaspers. “However, in the case of certain diseases, the father’s advanced age plays a relatively certain role.”
Older parents are more likely to pass on diseases
And while trisomy 21 is mainly due to the mother, about 20 hereditary diseases influenced by the father’s age have been identified. It plays a role in mental disorders such as schizophrenia or bipolar disorder.
Children conceived when the father is older are more likely to suffer from mental illness. Parents after age 45 are 3.5 times more likely to develop autism than those in their 20s.
Another hereditary risk is Antiphospholipid Syndrome (APS), a very serious autoimmune disease that can manifest itself in the form of pulmonary embolism, arthritis or memory impairment and epilepsy.
In addition, a 13fold higher prevalence of attention deficit disorder (ADD) was found in children of older parents and up to 25fold higher prevalence of bipolar disorder.
But there are advantages too
However, all this “can” and “must” not necessarily happen.
From a social point of view, late fatherhood can even have advantages: men are professionally stable, financially secure and have a good social network. When they are older, they can devote more time to their children than younger people who are still busy consolidating their careers, for example.
And even if the sperm of a 40, 50 or 60yearold man is no longer as fast as that of a young man, a father over 35 is perhaps a little more relaxed and also a little more generous when dealing with offspring. .
“A 60yearold man may only be 50 or 55 biologically according to his birth certificate. But of course it is questionable whether someone at 70 can still fulfill the role of father and really take care of his children like a 25 or 30yearold man,” observes LeiberCasters.