While recent research has warned of the potential drawbacks of America's declining fertility rate, a new study has found that having three or more children negatively affects late-life cognition.
"To the best of our knowledge, our study is the first to demonstrate a causal effect of higher fertility on late-life cognition," researchers Eric Bonsang and Vegard Skirbekk explain in their paper "Does Childbearing Affect Cognitive Health in Later Life? Evidence From an Instrumental Variable Approach" published in Demography, the flagship journal of the Population Association of America.
"We found that having three or more versus two children causes worse late-life cognition in Europe for both men and women. The negative effect of having three or more versus two children is large in magnitude, equivalent in our sample to being 6.2 years older and nearly the same as the cognitive advantage associated with having completed secondary versus primary education," researchers said.
The researchers used data collected from 73,353 participants who had only biological children spread across 19 European countries: Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, France, Germany, Greece, Hungary, Italy, Luxembourg, the Netherlands, Poland, Portugal, Slovenia, Spain, Sweden and Switzerland.
Participants provided information for the study through a computer-assisted personal interviewing program and a paper-and-pencil questionnaire.
Bonsand and Skirbekk said their findings suggest that if Europe reduces the number of people with three or more children, this could lead to better cognitive health in older adults.
"Given the magnitude of the effect, future studies on late-life cognition should also examine fertility as a predictor alongside more commonly researched predictors, such as education, occupational experiences, physical exercise, and mental and physical health. We also need more information on the types of interactions, supports, and conflicts that occur between parents and children, which may influence cognitive outcomes," the researchers said.
The study also noted that the adverse cognitive effect of having three or more versus two children was largest in Northern Europe relative to the other European regions despite Nordic countries having a higher standard of living.
Even though the standard of living is higher in Nordic countries, the cost of goods and services was three times higher, creating challenges for parents with more than two children.
"Having a third child in Northern Europe may therefore incur more financial costs (and potentially higher financial stress) than in many other regions. Moreover, the expectation that children should care for their aging parents may be lower in Northern Europe, where institutions are expected to provide support," Bonsand and Skirbekk noted.
The researchers also found that people whose first two children are of the same sex, two sons or two daughters, were more likely to have more than two children, but the probability was slightly higher among parents whose first two children are girls.
"People whose first two children are of the same sex have more children than people whose first two children are of mixed sex … they are also more likely to have three or more children relative to their peers whose first two children are of mixed-sex," the researchers said.
As the study only focused on the impact of having more than two children on late-life cognition, Bonsand and Skirbekk said future studies should examine the impact of having less than two children or none at all on late-life cognition.
They cited studies that suggest that "being childless (compared to having two children) is also related to worse late-life cognition for women."
"They (other researchers) argue that having children provides a source of interactions and promotes social activities that are associated with better cognitive functioning. However, other aspects of childlessness could have positive consequences for late-life cognitive functioning by posing fewer financial and time constraints during adulthood relative to having children," Bonsand and Skirbekk said.
American women are expected to have about 1.6 children in their lifetime, which is well below the population replacement level of 2.1 children per woman, recent research reported by The Christian Post shows.
Wendy Wang, director of research at the Institute for Family Studies, noted in a recently published research brief that without appropriate interventions, a continuous slide in the nation's fertility rate would lead to the aging and shrinking of the U.S. population. This would lead to a decline in productivity and instability in financing old-age programs such as Social Security and Medicare.