Taking acetaminophen during pregnancy not linked to autism or ADHD, study finds

Headlines in recent years have left many pregnant people unsure about a familiar medicine. Acetaminophen, also called paracetamol, is often the first drug clinicians suggest for pain or fever during pregnancy. Yet some studies, and a burst of political attention in September 2025, raised fears that prenatal exposure might raise a child’s chance of autism, attention-deficit hyperactivity disorder (ADHD), or intellectual disability.

Now, researchers at City St George's, University of London say the strongest available evidence does not support those worries. Their work, published in The Lancet Obstetrics, Gynaecology, & Women’s Health, combines results from dozens of studies and gives extra weight to designs that better control for family factors.

The study was led by Professor Asma Khalil, professor of obstetrics and maternal fetal medicine at City St George's, University of London and a consultant obstetrician. Her team reviewed the evidence to address public concerns that surged after claims in 2025 suggested acetaminophen might affect child brain development.

Past research has been messy. Some reports found small links between acetaminophen use in pregnancy and later diagnoses of autism or ADHD. But many of those studies faced limits. Some relied on incomplete exposure data. Others struggled to separate the medicine from the reason it was taken, such as fever, infection, or pain.

A central problem is confounding. If a pregnant person takes acetaminophen because of fever, the fever itself could matter for pregnancy and child outcomes. In that case, acetaminophen may look risky even if it is not the cause.

"Our research team focused on a design meant to reduce sibling comparisons. These studies compare siblings born to the same mother when one pregnancy involved acetaminophen and another did not. Because siblings share many genetic and home factors, the approach can reduce bias that standard observational studies cannot fully remove," Khalil shared with The Brighter Side of News.

To build their review, the researchers searched major medical databases through Sept. 30, 2025, including MEDLINE, Embase, the Cochrane Library, and ClinicalTrials.gov. They included only cohort studies in English that reported adjusted risk estimates. They excluded studies that offered only unadjusted comparisons.

They also graded each study’s risk of bias using the Quality In Prognosis Studies (QUIPS) tool. QUIPS checks several areas where studies can go wrong, including how exposure was measured and how well other influences were handled.

From an initial pool of 4,147 articles, the team ultimately included 43 studies in the systematic review. Seventeen were included in the meta-analysis, where results are pooled to estimate an overall effect.

The headline finding is straightforward. Across the sibling-comparison studies, acetaminophen exposure during pregnancy was not linked to autism, ADHD, or intellectual disability. The sibling-comparison datasets included 262,852 children assessed for autism, 335,255 for ADHD, and 406,681 for intellectual disability.

The pattern stayed the same when the researchers limited the analysis to studies rated at low risk of bias and to studies with longer follow-up periods, including those tracking children for more than five years. In other words, as the evidence got stronger, the apparent link weakened.

Khalil said the results help explain why earlier research sometimes looked alarming. "Our findings suggest that previously reported links are likely to be explained by genetic predisposition or other maternal factors such as fever or underlying pain, rather than a direct effect of the acetaminophen itself.

"The message is clear: Acetaminophen remains a safe option during pregnancy when taken as guided. This is important as acetaminophen is the first-line medication we recommend for pregnant women in pain or with a fever, and so they should feel reassured that they still have a safe option to relieve them of their symptoms."

The review also addresses a practical clinical concern. If pregnant patients avoid acetaminophen because of fear, they may leave pain or fever untreated. Fever in pregnancy, in particular, can carry known risks. The authors argue that confusion around acetaminophen could push people toward choices that are less safe.

Still, the researchers did not claim the evidence base is perfect. Many studies measured exposure differently, often through self-report. Outcome definitions also varied. Diagnostic criteria for autism and ADHD have changed over time, and some studies relied on screening tools rather than clinical diagnoses.

One major gap involves details that many families care about. The team could not analyze sibling-comparison data by trimester, the baby’s sex, or how often acetaminophen was taken. Too few studies reported those breakdowns in a way that allowed meaningful pooling.

Sibling comparisons also come with trade-offs. They can reduce bias tied to shared family background, but they may lose statistical power because only sibling pairs with different exposures inform the estimate. They also cannot fully address factors that change between pregnancies, like a new health condition.

Even with those limits, the authors describe the review as a high bar for this question because it relies on stronger designs and carefully grades bias. The overall conclusion supports guidance from major medical organizations that continue to recommend acetaminophen as the first option for pain and fever during pregnancy when used appropriately.

For patients, the findings offer reassurance in a space that has felt noisy and stressful. If you need relief from fever or pain during pregnancy, the best available evidence suggests acetaminophen remains a reasonable choice when taken as directed. That matters because untreated fever or severe pain can create real risks.

For clinicians and researchers, the study shifts the focus away from repeating weaker observational designs. Future work can help most by improving how exposure is measured, using pharmacy records or biomarkers, and by reporting timing and dose more clearly.

More family-based studies could also help separate the drug’s role from the conditions that prompt its use.

Research findings are available online in The Lancet Obstetrics, Gynaecology, & Women’s Health.

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