IInfection during pregnancy may be associated with having an autistic child simply because mothers of autistic children are prone to infections, a new study find.
Findings suggest ‘common infections during pregnancy do not appear to increase the risk of autism in their offspring,’ says study investigator Martin Brynge, psychiatrist and doctoral candidate in global public health at the Karolinska Institutet in Stockholm, Sweden. “Preventing maternal infections would probably not affect the prevalence of autism in the population.”
Much previous research has linked maternal infection during pregnancy to autism and intellectual disability in children. However, whether the former causes the latter has remained unclear. For example, autism and intellectual disability are linked to genetic variants that can influence the immune system, so mothers of children with either condition may also be more vulnerable to infections. serious.
See “Serious infections linked to autism: study”
The new study analyzed data from 549,967 children, including 267,995 girls, living in Stockholm County and born between 1987 and 2010; about 34,000 of the children had been exposed to a maternal infection requiring specialist health care, according to data from Sweden National Patient Registry and National Medical Birth Registry.
Among the exposed children, 3.3% are autistic, compared to 2.5% of the unexposed children, representing a 16% increase in the risk of autism.
But maternal infection in the year before pregnancy was also linked to a 25% higher risk of autism.
“Mothers who had an infection during pregnancy may not be comparable to mothers without an infection,” says Brynge. “There may be systematic differences at the group level.”
AOf the 394,093 children in the group who have full siblings, “siblings exposed to maternal infections were no more at risk for autism than their unexposed siblings,” says Brynge. In fact, maternal infection during pregnancy appears to be linked to a 6% lower risk of having autism in these siblings. The scientists detailed their findings online Sept. 7 in The Lancet Psychiatry.
Examining siblings and infections a year before pregnancy “are creative methodological approaches that help resolve remaining questions about association and potential causation,” says Stephane Buka, a professor of epidemiology at Brown University in Providence, Rhode Island, who was not involved in this study. When these other methodological approaches are considered, “the strength of the association for autism is more modest than previously reported.”
Maternal infection during pregnancy may be associated with autism, but perhaps not causally, the researchers say of the findings. “Our results contradict the well-established view that maternal infections cause autism,” says Brynge. “Mothers of children with autism have a higher propensity for infections in general, not just during pregnancy. So there appear to be unknown factors – genetic, environmental, or a combination of both – that increase susceptibility to infection in these mothers.
In contrast, the researchers could not rule out a potential causal link between maternal infection during pregnancy and intellectual disability. Compared to controls, women infected during pregnancy were 37% more likely to have a child with intellectual disability, while infection in the year before pregnancy was only 9% linked. more chances of having the same result. Data on siblings suggest that infection during pregnancy is associated with a 15% higher chance of having a child with intellectual disability.
The scientists caution that their findings do not rule out the possibility that rare infections, or relatively mild infections that do not require the specialized health care that the diseases in this study did, could cause autism or intellectual disability. For example, previous work has definitively linked rare infections such as rubella, Zika, and cytomegalovirus to an increased likelihood of intellectual disability.
“There remains the very real possibility that infection prevention will be effective in certain subgroups, particularly those at genetic risk for autism,” Buka says.
Previous research has also shown that antibodies in the mother that react with the central nervous system can increase the chance that a child have an intellectual disability, says Michael Benros, professor and head of research in biological and precision psychiatry at the University of Copenhagen in Denmark, who did not participate in this study. “Investigations of specific infections and central nervous system reactive antibodies in the mother during different trimesters of pregnancy and their associations with autism and intellectual disability are still warranted in large-scale studies,” says Benros. .
In the future, Brynge and his colleagues would like to investigate the potential effects of COVID-19, because the new study took place before the pandemic, he says. It would also be interesting to study why mothers of autistic children may have a greater risk of infections, he adds.
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This article was originally published on Spectrumthe main site for autism research information. |
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