Children born with certain infections acquired during pregnancy face substantially higher risks of autism and intellectual disability later in life, according to a study of more than 3.7 million people in Sweden.
Researchers found that children with congenital infections were about three times more likely to be diagnosed with autism and more than seven times more likely to receive a diagnosis of intellectual disability than those without such infections.
The findings suggest that infections transmitted from a pregnant woman to her foetus may have lasting effects on brain development, although the study identifies an association rather than proving that the infections directly cause autism or intellectual disability.
The research focused on TORCH infections, a group that includes syphilis, rubella, toxoplasmosis, cytomegalovirus and herpesvirus. These infections can cross the placenta and affect the developing foetus, potentially increasing the risk of miscarriage, stillbirth and other pregnancy complications.
“Although these congenital infections are rare, some of them can be prevented, which makes them important from a public health perspective,” said Reneé Gardner of the Department of Global Public Health at Karolinska Institutet, who contributed to the study.
The researchers examined people born in Sweden between 1987 and 2021 and followed them for up to 30 years. Among the 3.7 million participants, 975 had been diagnosed with a congenital TORCH infection.
Although congenital infections accounted for only a small proportion of autism cases across the population, the risk among affected children was considerably higher. The researchers estimated that about one in five children born with a TORCH infection could later develop autism.
The study also found elevated risks of intellectual disability across different levels of severity. The risk of severe to profound intellectual disability was as much as 30 times higher among children with a congenital infection than among those without one.
The researchers found evidence of an impact on educational outcomes even among people who were not diagnosed with autism or intellectual disability. A total of 420 participants with a TORCH infection showed poor school performance without receiving either diagnosis.
Congenital cytomegalovirus, or CMV, is the most common of these infections globally and affects roughly one in 150 newborns. Its burden is substantially greater in low- and middle-income countries.
The researchers said the findings highlight the importance of prevention, particularly in regions where these infections are more common. They pointed to vaccination programmes and other preventive measures as important tools for reducing congenital infections.
They also called for improved identification of affected newborns. Current screening systems, including those used in Sweden, may miss asymptomatic infections because universal screening for TORCH infections is not routinely carried out.
The authors said stronger screening and prevention strategies could help identify children at risk earlier and improve long-term support and care.
