Acetaminophen, one of the most widely used medications during pregnancy, may be linked to a higher risk of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) in children, according to a new review led by researchers at the Icahn School of Medicine at Mount Sinai.
The study, published August 14 in BMC Environmental Health, systematically analyzed 46 studies involving more than 100,000 mother–child pairs across multiple countries and found stronger associations in higher-quality research. Using the gold-standard Navigation Guide methodology, the team concluded that the evidence supports an association between prenatal acetaminophen use and increased incidence of neurodevelopmental disorders.
Widespread Use Meets Growing Concern
Known as paracetamol outside North America, acetaminophen is considered the safest option for pain and fever relief during pregnancy. More than half of pregnant women worldwide use it, often on medical advice, to treat headaches, muscle aches, or fever. Unlike other pain relievers such as NSAIDs, which can pose risks in pregnancy, acetaminophen has long been the go-to recommendation from professional bodies like the American College of Obstetricians and Gynecologists.
The Mount Sinai-led review challenges this long-standing perception. “Given the widespread use of this medication, even a small increase in risk could have major public health implications,” said Diddier Prada, MD, PhD, the study’s lead author. The team emphasized that their findings do not prove causation, but add weight to earlier research raising similar concerns.
How the Evidence Was Assessed
The Navigation Guide is a rigorous framework designed to evaluate environmental health risks. It assesses each study’s risk of bias, strength of evidence, and overall quality, providing a structured way to weigh findings from diverse research designs.
- Of the 46 studies reviewed, 27 reported positive associations between prenatal acetaminophen use and neurodevelopmental disorders.
- Twenty studies focused on ADHD, with 14 finding a significant link.
- Eight studies examined ASD, with five reporting a positive association.
- Several studies also found a dose–response relationship, suggesting higher risk with longer or more frequent use.
Prospective cohort studies, which track exposure in real time, generally produced stronger associations than retrospective analyses. The researchers also integrated biological evidence from laboratory and animal studies, which suggest acetaminophen can cross the placenta, trigger oxidative stress, disrupt hormones, and alter fetal gene expression.
Why Biological Mechanisms Matter
Experimental research offers plausible explanations for the observed associations. Acetaminophen reaches fetal circulation within an hour of maternal ingestion and is metabolized into compounds that can cause oxidative stress. This stress can interfere with brain development, while endocrine disruption and changes in DNA methylation may affect neural pathways linked to attention, learning, and social behavior. Such findings, the authors argue, reinforce the epidemiological data.
“Pregnant women should not stop taking medication without consulting their doctors. Untreated pain or fever can also harm the baby.”
Balancing Risks and Recommendations
The authors stress a cautious but balanced approach: avoid unnecessary use, choose the lowest effective dose for the shortest time, and consult healthcare providers. They call for updated clinical guidelines that consider these findings and for research into safer alternatives for pain and fever management in pregnancy.
While sibling-comparison studies have produced mixed results—sometimes finding no association—the authors note that these designs may suffer from exposure misclassification and reduced statistical power, potentially masking true effects. Overall, they conclude that the consistency of positive findings, combined with biological plausibility, supports applying the precautionary principle in clinical care.
Looking Ahead
With diagnoses of ASD and ADHD rising worldwide, the study’s implications extend beyond individual families to public health policy. Future research will need to refine exposure assessment, account for potential confounders, and identify the safest pain relief strategies during pregnancy. In the meantime, the message is clear: use acetaminophen during pregnancy only when necessary and under medical guidance.
Journal reference: Prada D, Ritz B, Bauer AZ, Baccarelli AA. “Evaluation of the evidence on acetaminophen use and neurodevelopmental disorders using the Navigation Guide methodology.” Environmental Health (2025). DOI: 10.1186/s12940-025-01208-0
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