Researchers from Karolinska Institutet examined health records for 3.7 million people born in Sweden between 1987 and 2021 to understand whether rare infections acquired in the womb are linked to autism and intellectual disability. The study tracked 975 children diagnosed with congenital TORCH infections—a category including cytomegalovirus, rubella, toxoplasma, and herpesvirus—for up to three decades to see if neurodevelopmental diagnoses emerged later in childhood.
TORCH infections are unusual because while most infections cannot cross the placenta to reach a developing fetus, these particular pathogens sometimes can, causing what doctors call a congenital infection.
Substantial Risk Increase for Affected Children
Children with congenital TORCH infections faced dramatically higher risks of later diagnosis. Those infected were approximately three times more likely to be diagnosed with autism than uninfected children. For intellectual disability, the risk was more than seven times higher, and for severe to profound intellectual disability, the risk rose as high as 30-fold.
At the individual level, researchers estimate that roughly one in five children born with a TORCH infection may later develop autism—a striking figure for those directly affected.
But These Infections Remain Rare in the Population
Despite these large relative increases, congenital TORCH infections are uncommon overall. The Swedish researchers estimate these infections account for only about 0.034 percent of autism cases nationally and roughly 1.2 percent of severe intellectual disability cases. This means that while risk is elevated for infected children, TORCH infections explain only a tiny fraction of autism and intellectual disability across the entire population.
This is the largest study to date examining the link between TORCH infections and autism, based on national register data covering nearly the entire Swedish population. Previous research on this connection has typically involved much smaller patient groups.
What This Means for Your Child's Health
- Ensure rubella immunity before pregnancy through vaccination if you haven't had it, as rubella is one TORCH pathogen with a preventable vaccine.
- Discuss food safety practices with your doctor during pregnancy—toxoplasma transmission is linked to undercooked meat and unwashed produce.
- If you develop symptoms of infection during pregnancy (fever, rash, or other concerning signs), seek prompt medical evaluation rather than assuming it's minor.