Rare congenital infections transmitted from mother to fetus significantly increase the likelihood of autism and intellectual disability in children, according to researchers at Sweden's Karolinska Institute, reports infohub.kz.
The scientists found that congenital TORCH infections triple the risk of autism and increase the risk of intellectual disability sevenfold. The results of the large-scale study, which covered data from 3.7 million people born in Sweden between 1987 and 2021, were published in the journal "JAMA Pediatrics."
The researchers focused on the TORCH group of infections, which includes cytomegalovirus, rubella, toxoplasmosis, and herpesviruses. Among all study participants, a congenital diagnosis was confirmed in 975 people.
The analysis showed that children with congenital infection had approximately a threefold higher likelihood of developing autism compared with children without the condition. The risk of an intellectual disability diagnosis was more than seven times higher, and severe forms of intellectual impairment were recorded 30 times more often.
According to the study's first author, Hugo Sjöqvist, this is the largest study to date in this field. The authors emphasize, however, that congenital infections are rare and account for only a small share of all autism cases in the population — about 0.034%. Yet on an individual level, autism is detected in roughly one in five children who have had a TORCH infection.
The researchers compared full siblings, which confirmed that the negative effect is caused by the infectious factor itself rather than shared family conditions. No link was found with other disorders such as ADHD.
Researcher Renee Gardner noted the need to prevent infection during pregnancy, including through supportive vaccination.