Study Questions Link Between Autism and Tylenol Use During Pregnancy

Findings follow new FDA requirement that all acetaminophen products carry a warning label urging pregnant women to use the drug with caution.

A new study adds more data to the ongoing scientific debate over whether using acetaminophen, the active ingredient in Tylenol, during pregnancy increases the risk of giving birth to a child with autism.

Researchers from the U.K., Italy, Sweden and Norway say they have reviewed current literature and found no evidence of “clinically important” increases in the risk of autism or other developmental disorders related to acetaminophen. Their findings, published in The Lancet Obstetrics, Gynaecology, & Women’s Health on January 16, are one of several such studies over the last several months.

Tylenol (acetaminophen) has been widely used during pregnancy for decades, largely because it has long been considered safe for unborn children. However, in recent years, several studies have reported associations between prenatal acetaminophen exposure and an increased risk of certain developmental disorders.

In September, the U.S. Food and Drug Administration (FDA) announced it was requiring new pregnancy label warnings for Tylenol and other acetaminophen-containing products. Health officials indicate that pregnant women should now be warned to use the drug with caution, and only when necessary. However, they have stopped short of recommending that women avoid Tylenol during pregnancy altogether.

That was followed by another study published in November in The BMJ, which determined the FDA and other researchers who found a link between Tylenol and autism relied on low quality evidence, leading to unreliable conclusions.

In the new study, researchers conducted a systematic review and meta-analysis of cohort studies drawn from multiple medical databases published through September 30, 2025, examining the estimated risk of autism spectrum disorder, ADHD and intellectual disability.

Led by Dr. Francesa D’Antonio from the University of Chieti’s Center for Fetal Care and High-Risk Pregnancy in Italy, the data ended up involving 43 studies in the systematic review and 17 studies in the meta-analysis, prioritizing those that looked at sibling comparisons. However, the researchers found no evidence of an increased risk of autism spectrum disorder, and no association between Tylenol pregnancy use and an increased risk of ADHD or intellectual disability.

“Current evidence does not indicate a clinically important increase in the likelihood of autism spectrum disorder, ADHD, or intellectual disability in children of pregnant individuals who use paracetamol as directed, supporting existing recommendations on its safety.”

— Dr. Francesa D’Antonio, Prenatal paracetamol exposure and child neurodevelopment: a systematic review and meta-analysis

Paracetamol is the European name for acetaminophen.

The researchers concluded that their findings bolster guidance on Tylenol use supported by the American College of Obstetricians and Gynecologists and other medical organizations, as opposed to those released by the FDA last year.

Tylenol Autism Lawsuits

The findings come as Johnson & Johnson, and other drug manufacturers, continue to face Tylenol autism lawsuits being pursued by families nationwide, each raising similar allegations that information about the risk of neurodevelopmental disorders linked to acetaminophen should have been disclosed to pregnant women.

These lawsuits were assigned to U.S. District Judge Denise Cote in the Southern District of New York in October 2022, as part of a multidistrict litigation for coordinated discovery and pretrial proceedings. 

However, in December 2023, Judge Cote issued an order excluding all of the plaintiffs’ expert witnesses, determining that the scientific theories and methods plaintiffs’ experts used to link acetaminophen to autism were not reliable enough to present to a jury. This led to the entire MDL being dismissed before any bellwether trials could take place.

Following the FDA’s new warning labels, plaintiffs filed updated briefing for their pending appeal in the Second Circuit Court of Appeals, arguing that the FDA’s new label requirements indicate that the science is good enough to require a warning from the nation’s leading drug regulatory agency, so it should also be good enough for a jury to consider the case. It is unclear when the appeals court will issue an opinion.

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