New Study Finds No Association Between Prenatal Acetaminophen Use and Autism or ADHD

A recent study published in JAMA Internal Medicine examined electronic health records from 2001 to 2023 for more than 700,000 mother-child pairs in Hong Kong, of which about 43 % were exposed to acetaminophen in utero. Using a sibling-matched design, researchers compared autism and attention-deficit/hyperactivity disorder (ADHD) outcomes among siblings where one was exposed to the drug during pregnancy and the other was not. The analysis included over 124,000 sibling pairs for autism and more than 97,000 pairs for ADHD.

The investigators reported no statistically significant association between prenatal acetaminophen use and either autism or ADHD, regardless of dosage, timing within pregnancy, frequency of use, or maternal age. When the sibling-matched approach was omitted, a modest association appeared, but additional "negative control" analyses—comparing children of mothers who used acetaminophen before conception or after delivery—also showed a similar pattern, which the authors described as biologically implausible.

"Collectively, these findings suggest that the positive signal observed in both conventional and negative control analyses reflect residual familial confounding, rather than a true pharmacologic effect of prenatal paracetamol exposure," the authors wrote.

The results align with earlier sibling-matched studies from Sweden (2024) and Japan (2025) that also found no causal link. The findings come after a September press conference in which President Donald Trump and health activist Robert F. Kennedy Jr. claimed acetaminophen could cause autism, a statement that had led to a measurable decline in its use among pregnant patients in the United States.

Medical societies have reiterated that acetaminophen remains a safe option for managing fever and pain during pregnancy, emphasizing that untreated fever itself poses risks to fetal development.