On Feb. 20, 2025, researchers from the University of Washington and Seattle Children’s Research Institute announced findings from a study showing prenatal exposure to acetaminophen increases the likelihood that a child will develop attention-deficit/hyperactivity disorder (ADHD), according to a study published in Nature Mental Health. 

Prior research shows that upward of 70% of pregnant women use acetaminophen during pregnancy to control pain or reduce fever. The drug, which is the active ingredient of many pain-relief medications, is one of the few considered safe to take during pregnancy by the U.S. Food and Drug Administration (FDA). 

Acetaminophen is widely used during pregnancy, with 41–70% of pregnant individuals in the United States, Europe and Asia reporting use. Despite acetaminophen’s classification as low risk by regulatory agencies such as the FDA, accumulating evidence suggests a potential link between prenatal acetaminophen exposure and adverse neurodevelopmental outcomes, including ADHD and ADHD autism spectrum disorder, the researchers noted. 

This research tracked a cohort of 307 women from 2006 to 2011, who agreed to give blood samples during their pregnancy.  The researchers tracked plasma biomarkers for acetaminophen in the samples.  The children born to these mothers were followed for 8 to 10 years. Among the women who did not use acetaminophen during pregnancy, the rate of ADHD was 9%, but for the women who used acetaminophen, the ADHD rate among their offspring was 18%.  

Acetaminophen metabolites were detected in 20.2% of maternal plasma samples. Children whose mothers had these biomarkers present in their plasma had a 3.15 times higher likelihood of an ADHD diagnosis compared with those without detected exposure. The association was stronger among daughters than sons, with the daughters of acetaminophen-exposed mothers showing a 6.16 times higher likelihood of ADHD while the association was weaker and nonsignificant in males. Researchers did not know why the association was stronger in females. 

Lead author Brennan Baker, a researcher at Seattle Children’s Research Institute, said that more work needs to be done to find out if some people can tolerate acetaminophen during pregnancy with no ill effects on the fetus while others cannot.  

He added that research findings on the effects of the drug and its potential risks during pregnancy have not been consistent.  One study recently released in Sweden, showed no link between maternal acetaminophen use and ADHD in their children; while another study out of Norway, did in fact find a link. The study out of Sweden, however, relied on self-reported data, Baker noted. 

“The study out of Sweden, however, reported that only 7% of pregnant individuals used acetaminophen,” Baker noted. “And that study could have underestimated the exposure. “I think it goes back to how the data was collected,” he added. “The conflicting results means that more research is needed.”