A new analysis published in The Lancet Obstetrics & Gynaecology & Women’s Health is offering critical reassurance to expectant parents: acetaminophen, commonly used to manage pain and fever during pregnancy, does not increase the risk of autism, ADHD, or intellectual disability in children. The complete study,utilizing a novel sibling-comparison methodology,directly addresses lingering public concerns – fueled in part by unsubstantiated claims made in recent years – and reinforces current medical guidance on pain management during pregnancy. Researchers emphasize that untreated fever and pain can pose risks to both mother and developing child, making informed medication choices essential.
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Taking acetaminophen during pregnancy does not increase the risk of autism, attention-deficit/hyperactivity disorder (ADHD), or intellectual disability in children. This is the conclusion of the most comprehensive analysis of the topic to date, published in the journal The Lancet Obstetrics, Gynaecology & Women’s Health. This research offers reassurance to pregnant individuals and healthcare providers amid ongoing concerns about medication safety.
The study arrives at a time of significant public discussion surrounding the issue. In September of last year, former President Donald Trump claimed that the use of Tylenol (the most common brand name for acetaminophen in the U.S.) by pregnant people could cause autism. The unsubstantiated claim was refuted by experts and medical organizations.
Despite being disproven, the statement fueled misinformation and anxiety among expectant mothers, particularly given that acetaminophen is one of the most widely used medications globally for relieving pain and fever during pregnancy.
How was the research conducted?
The work published in The Lancet is a systematic review and meta-analysis, a type of study that combines the results of multiple previous studies to reach a more reliable conclusion than individual studies could. In total, the authors analyzed 43 international studies.
When investigating medications during pregnancy, scientists cannot conduct controlled experiments deliberately exposing pregnant individuals to risks. Therefore, most evidence comes from observational studies, which analyze what happened in real-world scenarios. The challenge with this type of research is that comparisons between those who took the medication and those who did not can be unfair.
Acetaminophen is often used for pain, fever, inflammation, infections, and other conditions. These conditions themselves can affect the health of the pregnancy and the baby. Researchers refer to this as a “confounding factor”—something associated with medication use that can also affect the outcome being analyzed, creating an apparent link that isn’t necessarily causal.
Furthermore, because acetaminophen is available over-the-counter, many studies rely on questionnaires and self-reports from mothers. This introduces the possibility of memory errors and inaccuracies regarding dosage, frequency, and timing of use. The new review sought to overcome these limitations by prioritizing studies with a particularly strong design: comparisons between siblings.
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</div>Among the 43 studies included, the authors highlighted those that compared siblings born to the same mother in different pregnancies. The rationale is that siblings share a large portion of their genetics and grow up in a similar family environment. Therefore, if a mother used acetaminophen in one pregnancy but not another, this comparison helps reduce the influence of genetic and family context that could distort the results.
The comparative analysis between siblings included data from 262,852 children assessed for autism; 335,255 for ADHD; and 406,681 for intellectual disability. The result was consistent. When comparing pregnancies with and without acetaminophen exposure, there was no association with autism, ADHD, or intellectual disability.
“Our results suggest that previously reported associations are likely due to genetic predisposition or other maternal factors, such as underlying fever or pain, rather than a direct effect of acetaminophen itself,” said Professor Asma Khalil, professor of Obstetrics and Maternal-Fetal Medicine at City St George’s, University of London, and lead author of the study, in a statement.
Where did the distrust come from?
Concerns surrounding acetaminophen didn’t emerge suddenly. In recent years, some studies have suggested small associations between the use of the medication during pregnancy and an increased chance of an autism or ADHD diagnosis. For example, in 2025, a review published in Environmental Health analyzed 46 studies and found that 27 indicated some increased risk.
However, this type of result does not mean that acetaminophen causes autism. It may only indicate a correlation: mothers who took the medication may have had more fever, more infections, or more painful conditions during pregnancy, making them different as a group from those who did not take it.
One of the most cited studies in the debate was published in 2024 in JAMA. It analyzed nearly 2.5 million children born in Sweden between 1995 and 2019. In an initial analysis, there was a small difference: 1.53% of children exposed to acetaminophen in utero were diagnosed with autism, compared to 1.33% of those not exposed.
However, the result changed when researchers applied a more rigorous method, comparing siblings. In this analysis, the difference disappeared. In other words, the initial association likely reflected confounding factors, not an effect of acetaminophen itself.
A study involving approximately 200,000 children in Japan, also based on sibling comparisons, reached a similar conclusion. Another review, published in February in the journal Obstetrics & Gynecology, stated that “it is unlikely that intrauterine acetaminophen exposure confers a significant risk” of autism.
The *Lancet* review consolidates this trend: when looking at the strongest evidence, the link does not hold up. But even as the most complete work to date, it has limitations.
The authors explain that it was not possible to analyze important subgroups within the sibling comparisons in depth, such as the trimester of pregnancy in which acetaminophen was used; the baby’s sex; and the frequency with which the medication was taken.
This happened because many existing studies did not report this data in a standardized or detailed manner. In other words, the review answers the central question (whether there is an increased risk of autism, ADHD, or intellectual disability), but it still does not allow for a detailed breakdown of dose and timing with the same certainty.
Overall, the study’s findings reinforce recommendations already adopted by major health organizations. “The message is clear: acetaminophen continues to be a safe option during pregnancy when taken as directed. This is important, as acetaminophen is the first-line medication we recommend for pregnant individuals with pain or fever, and they should therefore feel reassured knowing they still have a safe option to relieve their symptoms,” said Khalil.
This does not mean that pregnant individuals should take any medication indiscriminately. The general recommendation remains the same: use the lowest effective dose for the shortest possible time and seek medical advice when in doubt, especially in cases of persistent fever, severe pain, or frequent need for pain relievers.
