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More intelligent men tend to become fathers later in life

According to a new study conducted by the University of Oslo’s Ragnar Frisch Center for Economic Research, intelligent men who score higher in IQ tests tend to become fathers later in life compared to those with a lower IQ.

However, the experts were surprised to find that they also tend to have more children than their less intelligent counterparts.

The researchers used Norwegian administrative registers with a large population covering to examine how male lifetime fertility patterns differ across cognitive score groups.

Their cohort consisted of over 900,000 Norwegian males born between 1950 and 1981. They had all undergone an army conscription intelligence test when they were teenagers. 

What researchers learned about intelligent men and fertility

The analysis revealed that those with higher IQs had their first child when they were older – but also had more children – compared to those with lower IQs. Moreover, in the lower scoring group, the scientists identified significantly higher rates of childlessness. 

“Men who scored in the top 20 percent of cognitive ability had their first child at the average age of 30 and went on to have a total of two children,” said study senior author Ole Rogeberg, a senior research fellow in Economics at the Frisch Center.

“Meanwhile men who scored in the bottom 20 percent had their first child at the average age of 27 and went on to have a total of 1.8 children.”

Other factors at play than just IQ scores

However, according to Nicky Hudson, a medical sociologist and director of the Center for Reproduction Research at De Montfort University, this phenomenon could also be influenced by factors other than IQ. These might include education trajectory and career.

Hudson said, “Studies have shown that people who remain in education longer, or who are from higher income groups, may have children later. But this is different from saying that childbearing is linked to some innate level of intelligence. Our research at the Center for Reproduction Research with men about their decisions to have children show this is complex and often related to finding a partner – as is the case with women.” Nicky Hudson was not involved in the study.

Moreover, with rises in living costs and increased work insecurity, it is not surprising that would-be parents may choose to delay having children until they become more financially secure.

Age and fertility of intelligent men

However, as Geeta Nargund – the director of Create Fertility warns – people who want children should be aware that age can have a significant impact on procreation capacities in both sexes. 

“For too long, fertility and the ‘biological clock’ has been viewed as solely a woman’s issue, but in fact around half of cases involve male factor infertility as a contributing factor. We see headlines of older male celebrities, such as Robert De Niro and Al Pacino, having children well into their golden years, but men must realize that these stories reflect the minority and not the norm,” she explained.

“Children born to men over 45 are five times more likely to have an autism spectrum disorder and 13 times more likely to be diagnosed with ADHD. The risk of miscarriage in women with male partners over 45 is twice as high as those with partners under 25.”

Thus, further research on fertility is necessary to clarify the relation between intelligent men, age and parenthood. An effort should be made to raise awareness about the various biological limitations older people might have to face should they decide to become parents. 

The study is published in the journal Biology Letters.

More about male fertility 

Male fertility refers to a man’s ability to cause pregnancy in a fertile woman. It depends on the quality and quantity of sperm that men produce, as well as the ability of the sperm to reach the egg. Several factors can influence male fertility:

Sperm production

A critical aspect of male fertility involves the quantity and quality of sperm produced. Men who produce too few sperm or sperm of poor quality may struggle with fertility. Factors like age, health, and lifestyle can impact sperm production.

Sperm delivery

Problems with sperm delivery can also affect male fertility. These could include sexual issues like premature ejaculation, genetic diseases like cystic fibrosis, damage to the reproductive organs, and blockages in the testicles.

Lifestyle factors

Certain lifestyle factors can also impact male fertility. These include smoking, alcohol use, drug use, environmental toxins, certain medications, and even prolonged exposure to heat (like in hot tubs or saunas).

Health factors

Certain diseases and health conditions can also affect fertility. These include hormone imbalances, infections, and conditions that can cause the body to produce antibodies that attack sperm.


While men can remain fertile for most of their lives, their fertility does begin to decline slightly after around age 40-45. This decline is usually due to decreased sperm quality rather than a decrease in sperm production.

Psychological factors

Stress, depression, and other mental health issues can interfere with hormones needed to produce sperm.

By Andrei Ionescu, Staff Writer

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