Children born to older mothers today tend to perform better on cognitive tests compared to their peers born to younger moms, according to a new study by researchers at the London School of Economics and Political Science (LSE) and the Max Planck Institute for Demographic Research (MPIDR).
The findings are a surprising twist compared to 40 years ago, when research showed that children born to older moms were at a disadvantage. According to the researchers, the shift may be due to the changing characteristics of women who have children at an older age.
Older mothers today tend to have several advantages — for example, they are typically well educated, are less likely to smoke during pregnancy and are often established in their careers. This was not necessarily true in the past.
Furthermore, more women are having their first child at an older age and, on average, first-born children perform better on cognitive ability tests. This may be because first-borns receive more resources and attention from parents than siblings born after them. In contrast, in the past, older moms were often having their third or fourth child.
For the study, researchers looked at data from three UK longitudinal studies — the 1958 National Child Development Study, the 1970 British Cohort Study and the 2001 Millennium Cohort Study. Children’s cognitive ability was tested when they were 10/11 years old.
In the 1958 and 1970 cohorts children born to mothers aged 25-29 scored higher than children born to mothers aged 35-39. In the 2001 cohort this result was reversed. Although the findings were similar for the children born to mothers over 40, the sample was smaller which means the findings should be treated with caution.
When the mothers’ social and economic characteristics were taken into account, however, the differences across cohorts disappeared. This indicates that the changing characteristics of women who have children at an older age were highly likely to be the reason for the cohort differences.
“Our research is the first to look at how the cognitive abilities of children born to older mothers have changed over time and what might be responsible for this shift,” said Dr Alice Goisis, a researcher at LSE and the lead author of the paper.
“It’s essential to better understand how these children are doing given that, since the 1980s, there has been a significant increase in the average age of women having their first child in industrialised countries.”
“Cognitive ability is important in and of itself but also because it is a strong predictor of how children fare in later life — in terms of their educational attainment, their occupation, and their health.”
The findings are published in the International Journal of Epidemiology.
Source: London School of Economics