A new study of Norwegian men finds that those with higher IQs tend to become fathers later than men with lower IQs. Surprisingly, the higher-IQ group also ended up with more children overall.
The Link Between Intelligence and Male Fertility
To investigate how male fertility patterns differ across cognitive groups throughout life, the researchers used extensive Norwegian administrative registers. Their sample included over 900,000 Norwegian men born between 1950 and 1981, all of whom took an army enlistment test during their teenage years.
The data analysis showed that men with higher IQs had their first child at an older age. They also had more children overall, while the group with lower IQ scores had significantly higher rates of childlessness.
As noted by lead author Ole Rogeberg in an interview with Earth, men with higher IQs had their first child at an average age of 30 and typically had two children. In contrast, men with lower IQs had their first child at an average age of 27.
Other Factors Beyond IQ
Medical sociologist Nikki Hudson, who leads the Center for Reproductive Research and did not take part in Rogeberg’s study, says other factors beyond IQ influence male fertility. Education and career status matter too.
Hudson says the findings may reflect that people who spend more time in education or who are in higher-income groups delay parenthood, rather than implying childbearing is tied to innate intelligence.
Her center’s research shows men’s decisions about having children are often influenced by difficulty finding a partner — a problem women face too.
Rising living costs and job insecurity also lead many potential parents to postpone children until they’re more financially secure. Many factors affect male fertility, from physical and mental health to lifestyle and age.
Age and Male Fertility
Despite the Norwegian study’s findings, Hita Nargunt, director of Create Fertility, warns that age can significantly impact fertility for both men and women. For a long time, fertility and the “biological clock” were viewed solely as women’s issues. However, nearly half of infertility cases involve male factors as well.
While men can remain fertile for most of their lives, their fertility begins to decline somewhat after the age of 40-45. Media headlines often feature celebrity fathers like Robert De Niro or Al Pacino having children at an advanced age. However, Nargunt explains that these stories represent a minority and are not the norm.
Children born to fathers over 45 are five times more likely to be diagnosed with autism spectrum disorder. Additionally, they are 13 times more likely to be diagnosed with attention deficit hyperactivity disorder (ADHD). The risk of miscarriage for women with partners over 45 is twice as high compared to those whose partners are under 25.
Further research is needed to clarify the relationship between intelligence, age, and fatherhood in men. Experts also emphasize the need to raise awareness about the biological limitations older prospective parents may face if they want to have children.
