Well, it looks like ‘mom brain’ continues long after pregnancy: A recent study found that parents with three or more children had a more pronounced decline in long-term brain health as opposed to parents of two children. The results suggest that there’s a relationship between having fewer than three kids and having a sharper mind later in life.  

The study was published in the journal Demography and was led by researchers at Columbia University Mailman School of Public Health and the Robert Butler Columbia Aging Center, and Université Paris-Dauphine-PSL. 

The researchers set out to assess whether higher rates of fertility had a causal effect on late-life cognition. To do so, they analyzed survey responses from representative populations in 20 European countries and Israel. Participants were aged 65 or older and had at least two biological children. 

A silver lining of shrinking family sizes

The birth rate in Europe is declining, which has led experts to worry about the health and viability of an aging population and a potential strain on the countries’ economic resources. 

“Understanding the factors that contribute to optimal late-life cognition is essential for ensuring successful aging at the individual and societal levels—particularly in Europe, where family sizes have shrunk and populations are aging rapidly,” says Vegard Skirbekk, PhD, professor of population and Family health at Columbia Mailman School, in a press release.

The study was the first of its kind to look at the relationship between fertility and long-term brain function. A 2014 study found that having a third child was detrimental to women’s mental health later in life, but not to men’s. 

After controlling for multiple variables, such as education and parents’ age at the birth of their second child, Dr. Skirbekk and his co-author Eric Bonsang, PhD, found that those adults with three or more kids performed worse on cognition tests like immediate and delayed word recall and verbal fluency. 

Related: 'Parent mode' may be hard-wired in our brains, say Harvard researchers

“The negative effect of having three or more children on cognitive functioning is not negligible, it is equivalent to 6.2 years of aging,” noted Dr. Bonsang, professor of economics at the Université Paris-Dauphine–PSL, in a statement.

Put plainly, having more children can negatively impact your long-term brain health and age your mind an additional 6.2 years. The effect was similar for both women and men. 

The results might not seem like good news, but the findings were promising to the researchers: Even though Europe’s population is declining due to a low birth rate, aging Europeans with fewer children might still be cognitively sharp late in life, maintaining their independence and reducing their future healthcare costs and long-term care needs. 

Related: The Great Baby Bust of 2022: Whay moms are deciding not to have more kids

How fertility can affect your long-term brain health

There are several ways fertility plays a role in brain health, but it essentially comes down to increased stress levels.  

Increased cost. It’s no secret that kids are expensive. Having more than three children can lead to an increased financial burden and reduced income and means you have a higher chance of falling below the poverty line, thereby decreasing the standard of living for all family members. The resulting financial worries and uncertainties could contribute to cognitive deterioration, write the study authors.

Less labor force participation. Having an additional child also causes women to participate less in the labor force, work fewer hours and bring home lower pay. Working, as compared with retirement, positively affects cognitive functioning among men and women, note the authors. 

Added stress. Parents with more children can experience more stress, have less time to relax and less time to invest in cognitively stimulating leisure activities. “This can imply sleep deprivation for the parent,” say the authors. 

Lower risk of social isolation. However, having more kids lowers your risk of being socially isolated in old age, which is a major risk factor for cognitive decline and dementia. 

Of course, what’s not included in this list is that having an additional child can bring so much increased potential for joy and happiness to your family. It’s a personal choice that should be based on the specific factors you want to prioritize. And there are plenty of other health benefits to having more kids: Another study found that moms who have more children might live longer.

While more research is needed, the authors argue that fertility should be considered a significant factor when it comes to long-term cognition alongside other predictors like exercise, job experiences, mental health and education. 

“In addition, future studies should address the potential effects of childlessness or having one child on late-life cognition. We also need more information on the types of interactions, supports, and conflicts that occur between parents and children, which may influence cognitive outcomes," adds Dr. Skirbekk.

Sources

Bonsang E, Skirbekk V. Does Childbearing Affect Cognitive Health in Later Life? Evidence From an Instrumental Variable Approach. Demography, 2022; doi:10.1215/00703370-9930490

Kruk KE, Reinhold S. The effect of children on depression in old age. Social Science & Medicine. 2014 Jan 1;100:1-1.