Large Swedish Study Identifies Congenital Infections as Risk Factor for Autism and Intellectual Disability

Researchers examining health records of 3.7 million people born in Sweden between 1987 and 2021 found that children diagnosed with congenital TORCH infections—including rubella, cytomegalovirus, and herpes simplex—had significantly higher rates of autism and intellectual disability diagnoses. The association persisted even when comparing affected children to their uninfected siblings, suggesting the link is not solely explained by shared family genetics. The study underscores the importance of vaccination and preventive measures to reduce these congenital infections.

Swedish researchers analyzed nearly four decades of birth records to examine whether prenatal exposure to a specific group of pathogens—those capable of crossing the placenta during pregnancy—might influence later neurodevelopmental diagnoses. The infections studied are well-established causes of intellectual disability, but their broader connection to autism had not been systematically quantified at the population level before this analysis.

The researchers employed a methodologically rigorous approach by comparing outcomes between infected children and their unaffected siblings, which helps isolate the infection's effects from other family-level factors that siblings would share. This design strengthens the evidence that the infections themselves, rather than genetic predisposition alone, drive the observed differences in diagnosis rates.