The Autism–Tylenol Pregnancy Question Finally Has a Clear Scientific Answer

After examining data from hundreds of thousands of children, researchers found no evidence that taking Tylenol during pregnancy raises the risk of autism, ADHD, or intellectual disability. The study suggests earlier warnings were driven by genetics or maternal illness rather than acetaminophen itself. Credit: Shutterstock

A massive new review finds that Tylenol use during pregnancy does not increase autism or ADHD risk.

Taking acetaminophen, commonly known in the US as Tylenol, during pregnancy does not increase the risk of autism, attention-deficit hyperactivity disorder (ADHD), or intellectual disability in children. This conclusion comes from the most thorough evaluation of the evidence to date, published on January 16 in The Lancet Obstetrics, Gynaecology & Women’s Health. The research was led by scientists at City St George’s, University of London.

A Comprehensive Review Addressing Public Concerns

To answer ongoing questions about safety, researchers conducted a systematic review and meta-analysis of 43 previously published studies. The effort was sparked by renewed public concern after claims in September 2025 suggested that taking acetaminophen during pregnancy could affect a child’s brain development and raise the risk of autism.

Those claims were largely based on earlier studies that reported small associations between acetaminophen use during pregnancy and autism diagnoses. Many of those studies, however, had important weaknesses. Some relied on limited data, while others failed to compare siblings, an approach that helps account for shared genetics and family background, both of which play a major role in child development.

Why Sibling Studies Strengthen the Evidence

The research team focused on studies that used the most rigorous methods available. They compared outcomes from pregnancies in which the mother used acetaminophen with those in which the medication was not used.

A key part of the analysis involved sibling comparison studies. These studies examined siblings born to the same mother, where one pregnancy included acetaminophen use and another did not. This design helps control for shared genetic factors, home environment, and long-term parental characteristics that standard studies often cannot fully address.

Large-Scale Data Shows No Increased Risk

The sibling comparison data included large numbers of children. Researchers reviewed information from 262,852 children assessed for autism, 335,255 evaluated for ADHD, and 406,681 assessed for intellectual disability. Across all of these outcomes, no link was found between acetaminophen use during pregnancy and an increased risk of any of these conditions when compared with pregnancies that did not involve the medication.

Expert Perspective on Earlier Findings

Professor Asma Khalil, Professor of Obstetrics and Maternal Fetal Medicine at City St George’s, University of London and Consultant Obstetrician, led the study and explained why earlier research may have raised concerns.

“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 paracetamol itself.

“The message is clear – paracetamol remains a safe option during pregnancy when taken as guided. This is important as paracetamol 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.”

Study Quality and Remaining Gaps

Each study included in the review was evaluated using the Quality In Prognosis Studies (QUIPS) tool, which examines multiple aspects of study design to assess the risk of bias. The absence of any association between acetaminophen use during pregnancy and autism, ADHD, or intellectual disability remained consistent even when the analysis was limited to studies considered low risk of bias (and therefore highest quality). The same results were seen in studies that followed children for more than five years.

The authors also noted some limitations. There was not enough detailed information to analyze outcomes based on the trimester in which acetaminophen was taken, the sex of the baby, or how frequently the medication was used, because too few sibling comparison studies reported those specifics.

What the Findings Mean for Expectant Mothers

Overall, the results support recommendations from major medical organizations around the world. The researchers hope this rigorous review will help reduce lingering doubts about using acetaminophen during pregnancy. Avoiding treatment for significant pain or fever can carry known risks for both mother and baby, especially when maternal fever goes untreated. This evidence reinforces that acetaminophen remains a safe option when used as directed.

Reference: “Prenatal paracetamol exposure and child neurodevelopment: a systematic review and meta-analysis” by Francesco D’Antonio, Maria Elena Flacco, Lorenza Della Valle, Smriti Prasad, Lamberto Manzoli, Athina Samara and Asma Khalil, 16 January 2026, The Lancet Obstetrics, Gynaecology, & Women’s Health.
DOI: 10.1016/S3050-5038(25)00211-0

Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.

View Original Article