Large Swedish Study Links Rare Congenital TORCH Infections to Higher Autism and Intellectual Disability Risks

The useful part

These Rare Infections During Pregnancy May Be Linked to Autism and Intellectual Disability, New Research Finds. The research followed nearly 3.7 million people born in Sweden across more than three decades, making it the largest investigation of its kind to date. The infections belong to a clinical group known as TORCH, a collection of pathogens that can sometimes cross the placenta and reach the developing fetus.

How it works

• While the infections are rare as congenital diagnoses, researchers found that children who were affected faced higher risks of developmental challenges.
• Researchers also estimated that around one in five children born with a TORCH infection may develop autism over time.
• The intellectual disability numbers were stronger than the autism figures, and the effects showed up in children who never received any formal diagnosis at all.
• Researchers estimated that these infections may account for about 1.2 percent of severe intellectual disability cases in Sweden.
• Researchers compared children with congenital TORCH infections to their own uninfected siblings and found that the elevated risk remained.

What to take from it

The findings also come with an important distinction: these infections may raise risk for some children, but they represent only a small portion of autism and intellectual disability cases overall. For severe to intellectual disability, the associated risk reached up to 30 times higher. Children with congenital TORCH infections had lower average grades than their peers, including children who never received a diagnosis of autism or intellectual disability.

Example or evidence

• They are not the same as the common illnesses many people experience during pregnancy.
• Children born with one of these infections were roughly three times more likely to receive an autism diagnosis later in life than children without them.
• That figure applies only to the affected group, not to the wider population.

Details worth keeping

Children With These Infections Were Three Times More Likely to Develop Autism The autism finding in the study is specific to the 975 people in the cohort diagnosed with a congenital TORCH infection at birth, not to children or pregnancies broadly. At the same time, the study found no association between congenital TORCH infections and either ADHD or obsessive-compulsive disorder. Children with congenital TORCH infections were more than seven times more likely to be diagnosed with intellectual disability than uninfected peers.

Related coverage

• Medicalxpress: How does autism develop? While genetics play a major role, researchers know that environmental factors during pregnancy also contribute to autism spectrum disorder.
• Medicalxpress: Pregnant women are routinely advised to avoid certain soft cheeses and take care when handling cat litter because of the risk of harmful infections.