Scientists Tracked 3.7 Million Births—One Rare Factor Was Linked to Autism - Newsweek
Children exposed to rare infections in the womb may face a higher risk of autism and intellectual disability, according to a major new study.
Researchers from Sweden's Karolinska Institutet found that babies born with congenital TORCH infections were about three times more likely to later be diagnosed with autism compared with children who were not infected.
They were also more than seven times more likely to develop an intellectual disability.
TORCH refers to a group of infections that can, in rare instances, be transmitted from a pregnant woman to her developing fetus.
The group includes infections such as cytomegalovirus, rubella, toxoplasmosis and herpes viruses.
Unlike many infections that remain confined to the mother, these pathogens can sometimes cross the placenta and directly affect the developing baby.
"It was already known that TORCH infections could be harmful in terms of intellectual disability, but we were surprised by the magnitude of the risks," lead author Hugo Sjöqvist, a Ph.D. student at Karolinska Institutet, told Newsweek. "Furthermore, that the infections' associations with autism remained, regardless of the intellectual disability status, was quite surprising."
The team discovered that children exposed to TORCH infections tended to have lower school grades at age 16, even if they were never diagnosed with autism or intellectual disability, Sjöqvist added.
To investigate the long-term effects, researchers examined nationwide data on 3.7 million people born in Sweden between 1987 and 2021.
Among them, 975 were diagnosed with a congenital TORCH infection at birth. The team then tracked participants for up to 30 years, looking for later diagnoses of autism, intellectual disability and educational outcomes.
The results of the study, published in JAMA Pediatrics, found that children born with a congenital TORCH infection had approximately three times the risk of autism and more than seven times the risk of intellectual disability compared with uninfected children.
The risk of severe-to-profound intellectual disability was even higher, reaching up to 30 times that of children without these infections.
Despite the elevated individual risk, the researchers emphasized that congenital TORCH infections remain rare.
As a result, their overall contribution to autism at the population level is relatively small.
While the findings are unlikely to explain a large proportion of autism cases, Sjöqvist said there are steps prospective parents can take now to reduce the risk of some infections.
"The different infection types have different prevalences depending on what country you look at," he explained. "In Sweden and the U.S., for example, cytomegalovirus (CMV) is the most common of the congenital infections, but concerningly rubella outbreaks have become more frequent in other parts of the world with a lower vaccine coverage."
A vaccination before pregnancy remains one of the most effective ways to prevent congenital rubella, Sjöqvist said.
"Unfortunately, we lack a vaccine for CMV, but general preventive [measures] such as good hand hygiene can help," he said. "Avoiding contact with young children’s saliva and urine can also reduce the risk of contracting it during pregnancy. Finally, avoiding undercooked/raw meat and washing vegetables is recommended to avoid toxoplasmosis. Also use care when handling cat feces."
Sjöqvist H., Dalman C., Mataix-Cols D., Gardner R.M., Karlsson H. Congenital TORCH Infections and Neurodevelopmental Outcomes. JAMA Pediatr. Published online September 21, 2026. doi:10.1001/jamapediatrics.2026.4229.
