A major new study out of Karolinska Institutet in Sweden, published September 21, 2026 in JAMA Pediatrics, has found that a group of rare infections that can pass from a pregnant woman to her developing baby, known as TORCH infections, are linked to significantly higher rates of autism and intellectual disability later in life. This is the largest study of its kind to date, and it comes with an important, actionable message: some of these infections can be prevented, and simple awareness of them may matter more than most expecting parents realize.
Here’s exactly what the study found, what TORCH actually stands for, which infections are preventable and how, and what to ask your OB.
Watch the Full Investigation Before You Read On
Before getting into the details of this research, there’s a documentary that explores broader questions around prenatal health and what expecting parents aren’t always told during routine care. Worth watching alongside this piece.
Click here to watch the MAHA film free
Click here to watch the MAHA film free
The Single Most Important Number in This Story
Before anything else, here’s the number that needs to anchor how you read the rest of this article: of the 3.7 million people born in Sweden between 1987 and 2021 included in this study, only 975 had a diagnosed congenital TORCH infection. That’s roughly 0.026 percent, an extremely small share of all pregnancies. The relative risk increases described below are real and statistically significant, but they apply to an already rare condition. This is a story about a serious risk for a small number of families, not a widespread threat to most pregnancies.
What the Study Actually Found
Researchers led by PhD student Hugo Sjöqvist, working with senior researcher Reneé Gardner at Karolinska Institutet’s Department of Global Public Health, used Swedish national health, birth, education, and death registers to track outcomes for the full population born over a 34-year period, including sibling comparisons to help account for shared genetic and environmental factors within families.
Children with a diagnosed congenital TORCH infection were about three times more likely to later be diagnosed with autism, more than seven times more likely to receive an intellectual disability diagnosis, and up to 30 times more likely to have severe to profound intellectual disability, compared to children without a congenital infection. Even among children with a TORCH infection who were not diagnosed with autism or intellectual disability at all, researchers found they received lower average grades in school than children without a congenital infection, suggesting effects on brain development may exist along a spectrum broader than formal diagnosis alone.
At the population level, researchers estimated that congenital TORCH infections account for approximately 1.2 percent of severe intellectual disability cases in Sweden, and about 0.034 percent of all autism cases nationally, reflecting just how rare these infections are even as their individual impact, when they do occur, is substantial. At the individual level, the researchers estimated that roughly one in five children born with a diagnosed TORCH infection may later develop autism.
Lead author Sjöqvist noted that while it’s long been established that these infections can cause intellectual disability, the specific link to autism had been less clear in prior research, largely because earlier studies were based on much smaller patient groups. This study, built on nearly complete national register data, represents the largest and most statistically robust look at this connection to date.
Why Researchers Believe These Infections Affect the Developing Brain
The proposed biological explanation for why TORCH infections specifically carry such elevated neurodevelopmental risk relates to their unusual ability to cross the placental barrier, a protective structure that normally shields a developing fetus from most infections circulating in the mother’s body. When a TORCH pathogen does cross that barrier, it can directly infect fetal tissue, including the developing brain, during critical windows of neurological development. This is part of why timing matters considerably with these infections, a first-time infection early in pregnancy, when the fetal brain and nervous system are undergoing their most rapid and sensitive development, tends to carry greater risk than a later infection or a case where the mother has pre-existing immunity from a past infection.
This mechanism also helps explain why researchers describe intellectual disability risk in this study as being even more strongly elevated than autism risk specifically, both conditions can result from disruption to fetal brain development, but the specific patterns and severity of disruption from a direct infection may affect a broader range of developmental domains than autism diagnosis alone tends to capture.
An Important Scientific Caveat
Co-author Gardner was careful to frame the findings honestly: these infections are uncommon, and they explain only a small share of autism cases overall, but for the children who are affected, the elevated risk of both autism and intellectual disability is clear and substantial. It’s also worth being precise that this is an association study, strengthened by sibling comparisons that help rule out some shared family factors, but it does not, on its own, prove that a TORCH infection directly causes autism in every affected child. The researchers themselves describe it as a strong, statistically robust association rather than definitive proof of individual causation.
What TORCH Actually Stands For
TORCH is a medical acronym referring to a group of infections capable of crossing the placenta and directly infecting a developing fetus, something most common infections during pregnancy don’t do. Here’s what each letter represents, along with what’s actually preventable:
T — Toxoplasmosis. Caused by a parasite often found in undercooked meat and cat feces. Prevention involves avoiding raw or undercooked meat during pregnancy, thoroughly washing produce, and taking care when handling cat litter, ideally having someone else handle litter box duties during pregnancy, or wearing gloves and washing hands thoroughly if that’s not possible.
O — Other infections, including syphilis. Prevention centers on prenatal screening and prompt antibiotic treatment if detected, since syphilis is both detectable through standard blood testing and treatable during pregnancy.
R — Rubella. One of the most directly preventable infections in this entire group. The MMR vaccine, given before pregnancy, provides strong protection, and researchers specifically highlighted that widespread rubella vaccination has virtually eliminated congenital rubella infection in Sweden, describing it as clear evidence of how effective preventive vaccination can be for protecting fetal neurodevelopment.
C — Cytomegalovirus (CMV). The most common congenital infection in this group, often transmitted through contact with young children’s saliva and urine, since CMV spreads easily in households and daycare settings with young kids. Prevention includes careful hand hygiene, avoiding sharing food, utensils, or cups with young children, and avoiding kissing young children on the mouth during pregnancy if you’re a CMV-negative caregiver of a toddler or young child in daycare.
H — Herpes simplex virus (HSV). Primarily a concern around the time of delivery, particularly with a first-time genital herpes infection late in pregnancy. Prevention and management involve open communication with your OB about herpes history, and antiviral medication during the final weeks of pregnancy if indicated.
What to Ask Your OB
Given that TORCH infections can often be asymptomatic in the mother, meaning you could carry one of these infections without feeling sick at all, awareness and proactive screening matter more than symptoms alone. A few specific things worth discussing with your OB or midwife:
- Ask directly whether TORCH panel screening is part of your prenatal care, and if not, ask why, since screening practices vary by provider, region, and individual risk factors, and it’s reasonable to ask the question directly rather than assume it’s automatically included.
- Confirm your rubella immunity status before or early in pregnancy, since this is typically checked through routine bloodwork and is one of the most preventable infections in this entire group if addressed before conception.
- Ask about CMV specifically if you have young children at home or work in childcare or healthcare, since these settings carry meaningfully higher CMV exposure risk.
- Discuss your herpes history openly, even if it feels uncomfortable, since proactive management late in pregnancy substantially reduces transmission risk during delivery.
- Ask about toxoplasmosis screening if you have cats or eat meat that isn’t always thoroughly cooked, since this is a straightforward blood test in most cases.
Why This Message Matters Beyond the Individual Risk
Gardner made a point of framing this research as an actionable public health priority specifically because, unlike many risk factors linked to neurodevelopmental outcomes, several TORCH infections are genuinely preventable through known, accessible measures, vaccination, hygiene practices, and screening, rather than being an unavoidable risk families simply have to accept. That’s a meaningfully different, more hopeful message than a lot of research into autism risk factors is able to offer, and it’s part of why the researchers emphasized prevention so directly in their own public statements about the findings.
What This Doesn’t Mean
It’s worth being just as clear about what this research doesn’t show. It doesn’t mean ordinary colds, flu, or common pregnancy infections carry this same risk, TORCH infections are a specific, distinct category of pathogens capable of crossing the placenta, not a general statement about infection during pregnancy. It doesn’t mean every child with a TORCH infection will develop autism or intellectual disability, roughly one in five did in this study, meaning the majority did not. And it doesn’t mean autism has a single infectious cause, TORCH infections account for a tiny fraction of a percent of all autism cases nationally, reflecting one of many factors researchers continue to study in a condition understood to involve a complex mix of genetic and environmental contributors.
Supporting a Healthy Pregnancy
For expecting parents focused on reducing preventable infection risk during pregnancy, a few practical, hygiene-focused steps beyond the OB conversation above:
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For households with young children at home during pregnancy, where CMV exposure risk is highest, Clearly Filtered offers water filtration systems that support overall household health as part of a broader hygiene-focused approach. Use code Welcome10 at checkout.
To be clear, these products address general household hygiene and cleanliness, not TORCH infection prevention specifically. Vaccination status, careful food handling, and hand hygiene around young children remain the most directly evidence-supported prevention measures discussed in this article. Always talk to your OB before starting any new supplement or product during pregnancy.
The Bottom Line
This is a genuinely important, well-designed study, and its core message deserves to reach expecting parents: TORCH infections are rare, but when they occur, they carry a substantial, well-documented risk to a child’s neurodevelopment, and several of them are meaningfully preventable through vaccination, hygiene, and proactive screening. The right response to this research isn’t fear, given how rare these infections actually are, it’s informed, practical awareness: know what TORCH stands for, confirm your rubella immunity, practice careful hygiene around young children and undercooked meat, and don’t hesitate to ask your OB directly about screening rather than assuming it’s automatically part of your care. For the vast majority of pregnancies, this research changes nothing about day-to-day routine, but for the small number of families it does affect, this kind of awareness can make a genuine, meaningful difference.
