Children born with a congenital TORCH infection face a much higher risk of serious developmental difficulties later in life. A study from Karolinska Institutet found that they were about three times more likely to receive an autism diagnosis and more than seven times more likely to be diagnosed with intellectual disability. For severe or profound intellectual disability, the relative risk reached as much as 30 times.
The study is one of the largest of its kind. It used national Swedish records covering 3.7 million people born between 1987 and 2021. The group included 975 people diagnosed with a congenital TORCH infection. Researchers followed participants for up to three decades, examining later diagnoses and school results. The study was published in JAMA Pediatrics.
These infections are uncommon. That limits their share of all autism and intellectual disability cases, even though the effects can be serious for affected children and their families.
TORCH refers to infections that can pass from a pregnant woman to the fetus. The group includes cytomegalovirus, rubella, toxoplasma and herpesvirus, among others. Unlike many common infections, these pathogens can sometimes cross the placenta and infect the fetus directly.
The Swedish researchers estimated that congenital TORCH infections could account for about 1.2% of all cases of severe intellectual disability. Their estimate for autism was much lower: approximately 0.034% of all cases in Sweden. At the same time, around one in five children born with a TORCH infection could later develop autism.
The study found effects beyond formal diagnoses. Children with a congenital infection received lower average school grades than their peers, even when they had not been diagnosed with autism or intellectual disability. The researchers found no clear links with other neuropsychiatric conditions such as ADHD or obsessive-compulsive disorder.
Family comparisons supported the result. Researchers compared children who had experienced a TORCH infection with siblings who had not. The associations remained similar, making it less likely that shared family circumstances alone explain the higher risks. The same distinction appears in earlier Alzheimer’s coverage, where individual risk was much higher than the condition's share of cases across the population.
Reneé Gardner of the Department of Global Public Health at Karolinska Institutet said the infections pass from mother to child only rarely and account for a very small proportion of all autism cases. Hugo Sjöqvist, the study’s lead author and a doctoral student, called it the largest study so far in this field because it uses national registers covering almost the entire Swedish population.
The public-health message is practical, not alarmist. Some of these congenital infections can be prevented. The researchers point to vaccination and other prevention strategies as safeguards during pregnancy. They specifically note that rubella has almost disappeared in Sweden since national vaccination programmes were introduced.
The evidence supports a focused response. Rare fetal infections do not offer a broad explanation for autism, yet their long-term effects still deserve serious attention. The study shows why prevention programmes matter and why children exposed to TORCH infections may need continued developmental and educational support long after birth.
