Children who are born to moms ages 35 to 39 perform significantly better on cognitive tests, according to a new study in the International Journal of Epidemiology.
Researchers analyzed three different studies conducted over 60 years to search for an association between the age of a mother and a child’s cognitive test results when he or she is in primary school.
The three studies — a 1958 National Child Development study, a 1970 British Cohort Study and the 2001 Millennium Cohort Study — each featured over 10,000 children. The cognitive tests administered measured the child’s ability to think, to read, to remember and to pay attention.
While the studies conducted in 1958 and 1970 discovered that the children born to women ages 25 to 29 scored better on the cognitive tests, the results of the 2001 study showed the opposite.
Children born to mothers ages 35 to 39 were more likely to fare better on cognitive tests in comparison to the children born to the younger moms in the study.
Why the change?
Today, older moms have led different lives than older moms of the past. In 2018, older moms are more likely to have received an education and are more likely to be able to support themselves financially than pregnant women over 30 in the past. Today’s over-30 moms have received more education, have generally higher incomes, are in stable marriages or relationships, live healthier lifestyles and are more likely to have planned their pregnancies.
The researchers explained that "over time, the women who gave birth at advanced maternal ages have become more advantaged than the women who gave birth at younger ages.”
And the study's lead author Alice Goisis said that cognitive ability is "a strong predictor of how children fare in later life -- regarding their educational attainment, their occupation, and their health."
Another recent study supports similar findings.
According to researchers from Aarhus University's School of Business and Social Sciences, when moms wait until their 30s to have children, the children are more likely to behave better and have a better psychosocial adaptation to life. The study included almost 5,000 moms and their children and analyzed their behaviors at ages 7, 11 and 15.
After controlling for external factors like socioeconomic status and education, the researchers found that children born to mothers in their 30s were more likely to develop greater patience as they aged.
The researchers also found that older moms are more patient than younger moms, and they were found to use less harsh verbal and physical punishment tactics.
"The [older] mothers have more psychological flexibility, more cognitive flexibility, more ability to tolerate complex emotional stimuli from the children," Tea Trillingsgaard, an associate professor of psychology at Aarhus University in Denmark and lead author on the study, explained.
"This style of parenting can thereby contribute to a positive psychosocial environment which affects the children's upbringing," added study co-author Professor Dion Sommer.