Rare Prenatal Infections Linked to Higher Autism and Intellectual Disability Risk

The Magnitude of TORCH Infection Risks

The acronym TORCH groups several rare infections that can be transmitted from a pregnant woman to her developing fetus, crossing the placenta directly. According to the Karolinska Institutet study, the group includes cytomegalovirus (CMV), rubella, toxoplasmosis, and herpes viruses. Among the 3.7 million people tracked for up to 30 years, researchers identified 975 people diagnosed with a congenital TORCH infection at birth.

The data revealed that these children were more than seven times more likely to develop an intellectual disability compared to uninfected peers. Lead author Hugo Sjöqvist, a Ph.D. student at Karolinska Institutet, noted to Newsweek that while researchers knew these infections could harm intellectual development, the sheer magnitude of the risks came as a surprise. Sjöqvist also pointed out that the association between the infections and autism remained present regardless of whether the child had an intellectual disability.

Educational Impacts and Severity

Beyond formal diagnoses of neurodevelopmental conditions, the study tracked long-term educational outcomes. Researchers found that children exposed to congenital TORCH infections tended to achieve lower school grades at age 16, even if they never received an autism or intellectual disability diagnosis. For the most severe outcomes, the numbers escalated dramatically; the risk of severe-to-profound intellectual disability reached up to 30 times that of uninfected children.

Despite these high individual risk ratios, the researchers emphasized that congenital TORCH infections remain fundamentally rare. Consequently, their overall contribution to autism cases at the population level is relatively small. Sjöqvist explained to Newsweek that infection types vary by region, noting that CMV is the most common congenital infection in Sweden and the United States, while rubella outbreaks have increased in areas with lower vaccine coverage.

Prevention and Public Health Measures

Sjöqvist noted that vaccination prior to pregnancy remains one of the most effective ways to prevent congenital rubella. For cytomegalovirus, which lacks a vaccine, general hygiene practices such as frequent handwashing and avoiding contact with young children’s saliva and urine can help lower the risk of transmission during pregnancy. Additionally, health guidance advises thorough washing of vegetables, avoiding raw or undercooked meat, and exercising caution when handling cat feces to prevent toxoplasmosis.