1.5 Million Weigh in on Acetaminophen-Autism

Acetaminophen causing autism? Another negative study

STUDY: Prahm KP et al, JAMA Pediatrics 2026; 

STUDY TYPE: Nationwide cohort study with sibling analysis

FUNDING: The Capital Region of Denmark Research Fund and Herlev Hospital Research Fund

Background

Here’s where we stand on the acetaminophen-autism link. Some studies found a small signal, but it disappeared when accounting for the fact that women who take this pain reliever are more likely to have health problems. Now, let’s see what the new report from Denmark shows.

The Study

• 1.5 million children born between 1997 and 2022.
• Children whose mothers filled a prescription for acetaminophen during pregnancy were compared to those with no prenatal exposure.
• A sibling analysis compared children with different in-utero exposures from the same mother, which helps control for shared genetic and family factors.
• Autism diagnoses were tracked from age one through July 2023.

Results

After adjusting for maternal age, comorbidities, psychiatric history, and other medications, acetaminophen exposure did not raise autism risk. The adjusted hazard ratio was 1.03 in the full population and 1.09 in the sibling analysis, both statistically non-significant. No dose-response pattern emerged. Low, medium, and high daily doses all showed hazard ratios near 1.0. Timing didn’t matter either: first, second, and third trimester exposures produced similar null results.

Practice Implications

1. Acetaminophen use during pregnancy does not cause autism.
2. Untreated fever in pregnancy, particularly in the first trimester, poses serious risks like neural tube defects (spina bifida, anencephaly), cardiac malformations, oral clefts, miscarriage, premature labor, and cognitive or developmental issues in the child.
3. Acetaminophen treats fever.