Tylenol na gravidez não mostrou ligação com autismo em estudo com irmãos
by Sanjukta Mondal, Medical Xpress
edited by Sadie Harley, reviewed by Robert Egan
This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:
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Tylenol (also known as acetaminophen or paracetamol) is one of the most widely used over-the-counter options for easing pain and reducing fever, including during pregnancy. More recently, safety concerns around use during pregnancy have gained attention, with claims of a possible link between prenatal exposure and autism in children increasingly appearing in news headlines and prime-time debates.
A two-decade-long, large-scale study from Hong Kong found no evidence of links between taking paracetamol (acetaminophen) during pregnancy and an increased risk of autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD) in children.
The scientists used a statistical method called a sibling-matched design to analyze more than 708,020 mother-child pairs in Hong Kong. By comparing siblings within the same family, where one was exposed to paracetamol in the womb and the other was not, they could better isolate the drug's effect while accounting for shared genetics and home environment that might otherwise bias the findings.
The finding of no link to ASD or ADHD held true regardless of dose or timing. It didn't matter whether mothers took a little or a lot, or whether they took it in the early weeks or the final stretch of pregnancy.
The findings are published in JAMA Internal Medicine.
Familial factors or paracetamol?
Tylenol's, or paracetamol's, safety during pregnancy is back in the spotlight after the U.S. president claimed it increases the risk of autism in children. The concern stems from observational studies reporting a possible association between prenatal paracetamol exposure and conditions such as autism (ASD) and ADHD.
While the remarks reignited public concern, health authorities, including U.K. regulators and the World Health Organization, continued to state that paracetamol is safe to use during pregnancy when taken as directed.
Earlier reviews found that the reported association could be influenced by the reason paracetamol was prescribed, rather than the drug itself, making it difficult to determine whether the medication truly increases risk. Even the FDA news release warning about the risks of Tylenol noted that the studies that established the association did not prove causation and may have been influenced by other factors.
A clear pattern emerged across the studies focusing on this topic. Conventional cohort studies have often reported a link between prenatal paracetamol exposure and ASD or ADHD, but that association largely disappeared in sibling-controlled studies after accounting for shared family factors.
In this study, the researchers compared siblings where the mother had taken paracetamol during one pregnancy but not the other, allowing them to cancel out shared family factors. They used official prescription records to track which trimester the medicine was taken in, the frequency of use and the dosage. The team followed the children for many years, in some cases up to 23 years, to see if they had developed ASD or ADHD.
After analyzing the data from more than half a million people and accounting for shared family factors, the researchers found no association between paracetamol use and ASD or ADHD. Even when one child was exposed to the medicine and their sibling was not, their risks were the same.
Risks of avoiding treatment
To further test the findings, researchers also looked at mothers who took paracetamol before they got pregnant or after giving birth. Their children showed similarly small increases in risk, suggesting that shared family factors, rather than exposure to the medicine in the womb, could explain the association.
Based on the findings, paracetamol remains a safe and essential option for treating pain and fever during pregnancy when used as directed. The researchers cautioned that avoiding it could leave fevers untreated or lead to the use of alternative medications, such as ibuprofen or opioids, and both of those factors are known to pose greater risks to the developing baby.
Written for you by our author Sanjukta Mondal, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.
Shan Luo et al, Prenatal Acetaminophen (Paracetamol) Use and the Risk of Autism and/or Attention-Deficit/Hyperactivity Disorder Among Sibling-Matched Cohorts, JAMA Internal Medicine (2026). DOI: 10.1001/jamainternmed.2026.2215
Journal information: JAMA Internal Medicine
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