Study Finds No Link Between Acetaminophen Use During Pregnancy and Autism or ADHD Risk

A new study has found no evidence to support claims that acetaminophen, the active ingredient in Tylenol, which is widely used to treat pain and fever during pregnancy, increases the risk of autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD) in children.
On June 30, a research team led by Professor Eric Yuk-fai Wan of the University of Hong Kong and Professor Ian Chi-kei Wong of Aston University in the U.K. published findings in the JAMA Internal Medicine. After analyzing 708,020 mother-child pairs in Hong Kong, the team reported that they found no association between the use of acetaminophen during pregnancy and the development of ASD or ADHD in children.
Acetaminophen is recommended worldwide as a first-line medication for treating pain and fever during pregnancy.
However, concerns have been consistently raised that because the drug crosses the placenta, it could potentially affect fetal neurodevelopment.
Some observational studies have reported results suggesting that use during pregnancy is linked to an increased risk of ASD or ADHD in children. Public interest grew further after former U.S. President Donald Trump claimed that using Tylenol during pregnancy could increase the risk of autism spectrum disorder in children.
The research team established a cohort of 708,020 mother-child pairs using electronic medical records from Hong Kong's public healthcare system from 2001 to 2023. They compared the risks of ASD and ADHD among siblings who had different levels of exposure to acetaminophen during pregnancy.
The analysis included 124,333 individuals for ASD and 97,285 for ADHD.
The research team explained that sibling comparison studies allow for the control of confounding factors within the household, as siblings share genetic factors and home environments.
The results showed that the use of acetaminophen during pregnancy was not associated with an increased risk of autism spectrum disorder [adjusted hazard ratio (aHR) 1.00] or attention-deficit/hyperactivity disorder (aHR 1.01) in children.
Furthermore, no significant increase in risk was found even when analyzing by the timing of acetaminophen use (first, second, or third trimester), usage patterns (use during one period, two periods, or throughout the entire pregnancy), and cumulative dosage.
In addition, while a general cohort analysis did observe an association between Tylenol and an increased risk of ASD and ADHD, the same result appeared even with use before pregnancy, when the drug could not have affected the fetus.
The research team stated that this sibling comparison study found no evidence of an association between Tylenol use during pregnancy and the risk of ASD or ADHD, suggesting that the associations reported in previous studies were likely influenced by common family factors rather than the drug itself.
They added, "This study strengthens the evidence that prenatal acetaminophen exposure is not a major risk factor for ASD and ADHD in children," and "It provides important evidence that using Tylenol during pregnancy is safe when medically necessary."
(Photo: AP, Yonhap News)
※ Please note: This article was translated by AI and may contain errors.