Acetaminophen use throughout being pregnant isn’t prone to increase the danger of getting a toddler with autism, ADHD, or mental incapacity, based on a brand new research printed Friday.
Researchers throughout Europe reexamined proof from a number of research investigating the hyperlink between these situations and the usage of paracetamol — known as acetaminophen in the US — and located that these purported associations fell aside after controlling for confounding components.
Acetaminophen, the lively ingredient in Tylenol, has lengthy been a frontline treatment for relieving ache or fever in people who find themselves pregnant. The scientific literature reveals that this follow shouldn’t change, mentioned co-author Asma Khalil, obstetrics and maternal fetal medication professor at St. George’s Hospital, College of London.
“The message actually is obvious,” mentioned Khalil. “Paracetamol stays a protected possibility throughout being pregnant when taken as guided — for the period that’s wanted, with an accurate dose.”
Impartial well being specialists praised the research’s strategies and conclusions, which diverge sharply from the suggestions supplied by President Trump and prime well being officers in September, after they mentioned that acetaminophen needs to be used provided that completely wanted throughout being pregnant and launched a nationwide public data marketing campaign to tell medical doctors and households of the purported danger. Their announcement got here as a part of their bid to search out the reason for autism, which many years of analysis has already linked to primarily genetic components.
The findings of this new research, printed in The Lancet, are unlikely to alter these suggestions. Well being and Human Providers officers mentioned the research didn’t refute claims from different researchers.
Extra on acetaminophen
“Many specialists have expressed concern of the usage of acetaminophen throughout being pregnant, together with Dr. Andrea Baccarelli, the Dean of the Harvard College of Public Well being,” mentioned HHS spokesperson Andrew Nixon.
The U.S. authorities is an outlier in discouraging acetaminophen use — the American School of Obstetricians and Gynecologists, its British counterpart the Royal School of Obstetricians and Gynaecologists, in addition to the European Medicines Company proceed to suggest the drug as a first-line remedy for ache and fever in pregnant individuals.
The U.S. well being officers’ stance that publicity to acetaminophen throughout being pregnant is related to autism spectrum dysfunction spurred the European researchers into a brand new evaluation of the obtainable proof. Acetaminophen is a vital device for physicians, the go-to drug to make use of throughout being pregnant as a result of different generally obtainable painkillers, corresponding to Advil (ibuprofen), and opioid medicines can put a fetus susceptible to kidney harm, preterm start, and even stillbirth. Acetaminophen isn’t just a ache reliever for people who find themselves pregnant, it additionally mitigates fevers that may improve the probability of start defects.
Scientists have had ample time to research the potential opposed outcomes of acetaminophen, a drug first used clinically in 1893, a lot in order that “there is perhaps extra critiques of acetaminophen research than precise acetaminophen research with major knowledge,” quipped Brian Lee, a professor of epidemiology at Drexel College. Typically, they’ve discovered that the advantage of acetaminophen outweighs the danger related to utilizing it. Why, then, did Khalil and her group add one other meta-analysis to the massive pile of research?
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Lee and different specialists see the Lancet paper as a direct rebuke of a meta-analysis printed in 2025 and co-authored by Baccarelli. The 2 papers analyze lots of the identical research, however the 2025 evaluation arrived at a drastically totally different conclusion, discovering “vital hyperlinks” between acetaminophen use throughout being pregnant and elevated dangers of situations like autism or ADHD. Baccarelli’s paper was cited by prime well being officers in September, saying that the dean has established a “causal relationship” between the drug and these opposed outcomes.
Baccarelli has thus far declined to touch upon well being officers citing his work to induce warning in the usage of acetaminophen, or in regards to the paid testimony he has given to strongly assert a hyperlink between acetaminophen use throughout being pregnant and situations like autism. A Harvard T.H. Chan College of Public Well being spokesperson mentioned Baccarelli was unavailable to debate the brand new Lancet research.
Authors of the brand new Lancet research winnowed down 1000’s of printed papers to 43 research primarily based on danger for “bias,” or how totally papers’ research designs and protocols accounted for confounding components, corresponding to genetics. The authors prioritized research wherein a mom took acetaminophen throughout one being pregnant, however not one other. If autism or different neurodevelopmental outcomes have been related to an environmental issue corresponding to taking Tylenol, then researchers would discover that differential within the siblings’ neurodevelopmental outcomes.
However that’s not what the researchers discovered, particularly when evaluating the info from two notable research out of Sweden and Japan, which used this technique throughout huge datasets. When the researchers carried out a meta-analysis of those and 15 different papers, they discovered no affiliation between maternal acetaminophen use and a heightened danger of autism, ADHD, or mental incapacity.
David Mandell, a professor of psychiatry on the College of Pennsylvania’s Perelman College of Drugs, applauded the Lancet research’s sturdy design and dedication to controlling for confounding variables, calling it a “fairly stable rebuke” of Baccarelli’s paper, which devalued sibling management research in its evaluation.
“As a lot as there exists a scientific greatest follow to conducting critiques and meta-analyses, they’re nonetheless very a lot utterly ensuing from subjective interpretation,” mentioned Lee. “Magnificence is within the eye of the beholder, however in contrast with the horrifically inaccurate Prada et al. evaluation, this can be a vital enchancment.” (Diddier Prada, an assistant professor of inhabitants well being science and coverage at Mount Sinai’s Icahn College of Drugs, was a co-author on the Baccarelli 2025 paper.)
What the proof tells us about Tylenol, leucovorin, and autism
The conflicting conclusions of Baccarelli’s paper and this paper from European researchers spotlight the vital decisions that scientists make when crafting a research. There’s no good design that eliminates all confounders, particularly when sifting by way of the infinite variables that affect being pregnant and the historic omission of pregnant individuals from medical trials.
Sibling management research like these out of Sweden and Japan have turn into a standard in epidemiological circles on the backs of a tantalizing promise: having the identical mom means an affiliation discovered between, say, Tylenol and autism will probably be free from the confounding components fixed between pregnancies, corresponding to genetics, socioeconomic standing, and extra. You probably have a big sufficient dataset, you’ll be able to deal with vital well being questions.
Zeroing in on this particular kind of differential publicity inside a household has limits, corresponding to excluding households with a single little one. It may possibly additionally bias outcomes towards the null, which means towards discovering no affiliation between acetaminophen and sure disabilities. Nationwide Institutes of Well being Director Jay Bhattacharya raised these factors when excoriating siblings research on social media in September.
However the limitations minimize each methods, mentioned Jonathan Sebat, professor of psychiatry and mobile biology on the College of California, San Diego. Observational research like those favored in Baccarelli’s meta-analysis can overestimate the existence of an affiliation. He mentioned it’s vital to make use of a research design that controls for genetic components when autism is principally inherited, including that it’s laborious to summarily dismiss these sibling cohort research when their accounting for genetic and familial confounding didn’t simply weaken the affiliation. It disappeared.
“That image isn’t very supportive of the speculation,” mentioned Sebat. “I want much more proof now to actually consider that there’s an acetaminophen affiliation.”
The myriad components that affect little one improvement might complicate a definitive pronouncement corresponding to Tylenol use doesn’t trigger autism or different neurodevelopmental issues. However well being specialists say the most recent evaluation of proof reveals that physicians ought to proceed to make use of acetaminophen to deal with ache and fevers throughout being pregnant.
“This [study] confirmed that there is no such thing as a relationship between taking paracetamol in being pregnant and a better probability of autism, ADHD, or mental disabilities within the offspring,” mentioned Grainne McAlonan, a translational neuroscience professor at King’s School London. “Whereas the influence of final 12 months’s announcement has been intensive, I hope the findings of this research convey the matter to a detailed.”
