Children born from in vitro fertilization score higher on reading and verbal tests than other kids, according to a new study. The findings cast doubt on prior research suggesting IVF babies have lower cognitive abilities. The new data also suggests that artificially conceived babies tend to have older, more educated, and wealthier parents—all boons for childhood intelligence.
“The positive effect of the family background of children conceived through artificial reproduction techniques ‘overrides’ the risks of related poor health impairing their cognitive ability,” said coauthor on the study Melinda Mills of the University of Oxford, in a statement. “The findings support other studies showing that on balance such fertility treatments do not impair a child’s higher thinking skills.”
More than five million children have been conceived through IVF since the first successful artificial fertilization in 1978, and scientists have been tracking the development of these children ever since. The results have been a mixed bag—some studies suggest IVF babies suffer from impaired behavioral, emotional, and cognitive development, but larger meta-analyses suggest that, whatever differences exist between IVF babies and other kids are likely due to outside factors. Children conceived through IVF tend to have lower birth weights and higher rates of birth defects, for instance, two factors that are also linked to delayed cognitive development.
For this new study, Mills and colleagues analyzed data from 8,298 artificially conceived children born in the UK between 2000 and 2001, who sat for cognitive ability tests in verbal and reading skills every two years until 2012. When the researchers compared these children’s scores with that of kids conceived naturally, they were surprised to find that the IVF babies scored higher than other children—but that the scores evened out by the time the kids were 11 years old.
Mills and her team suspect that IVF babies may score higher initially because, whatever drawbacks come from being artificially conceived (such as low birth weight), there are even more advantages. Indeed, studies suggest adults who conceive through IVF tend to be wealthy and highly educated—two factors known to influence child cognition. It also doesn’t hurt that parents, aware of the studies that suggest their IVF babies could fall behind, tend to be more attentive and put herculean effort into making sure their kids remain intellectually stimulated.
As for why even that advantage seems to peter out by age 11, Mills and colleagues have yet another theory—once it becomes clear that a child is developing normally, parents tend to relax. “Parents may perceive their children as more fragile but once past the period of greatest risk, their parenting style may change to become more like other parents,” Anna Barbuscia, also of the University of Oxford, said in the press release. “This might account for the fact that the gap in higher cognitive ability has closed by the time both groups of children had reached the age of 11 with only slightly better scores for artificially conceived children at this later stage.”