JAMA: Congenital Infections Linked to Increased Risk of Intellectual Disability

Researchers at the Karolinska Institute in Sweden have found an association between rare infections that can be transmitted from a pregnant woman to her fetus and an increased risk of autism and intellectual disability in children. The findings were published in JAMA Pediatrics.

The researchers analyzed data from 3.67 million people born in Sweden between 1987 and 2021. Among them, 975 were diagnosed with congenital TORCH infections. This group includes infections that can be transmitted from mother to fetus during pregnancy or during delivery. TORCH infections include toxoplasmosis, rubella, cytomegalovirus (CMV), herpes, syphilis and several other infections. The participants were followed for nearly three decades.

Compared with people who did not have such infections, those with congenital TORCH infections had approximately a 3.1-fold higher risk of subsequently being diagnosed with autism and a 7.2-fold higher risk of intellectual disability. For severe and profound intellectual disability, the relative risk was even higher, reaching up to 30-fold. The researchers found similar results when they compared affected children with their siblings.

“TORCH infections themselves are rare. They account for only a small proportion of autism cases in the population — about 0.034%. Therefore, these findings do not mean that most cases of autism are linked to infections during pregnancy,” the researchers noted.

According to the authors, the findings highlight the importance of preventing infections that can be transmitted from pregnant women to their fetuses, including vaccination against preventable infections and other preventive measures.