Exposure to acetaminophen during pregnancy may be associated with an increased likelihood of children developing neurodevelopmental disorders (NDDs), including autism and ADHD, according to a new study. Acetaminophen is a common active ingredient in pain and fever relievers, most widely recognized under the brand name Tylenol.
The study was recently published in BMC Environmental Health. The senior author was Andrea Baccarelli, dean of the faculty and professor of environmental health at the Harvard T.H. Chan School of Public Health. The research was led by the Icahn School of Medicine at Mount Sinai.
The team analyzed data from 46 previous studies conducted worldwide. They employed the Navigation Guide systematic review methodology—a rigorous framework considered a gold standard in environmental health research—to conduct a comprehensive analysis. This robust approach supported the evidence of an association between prenatal acetaminophen exposure and an increased incidence of NDDs.
Key Findings and Recommendations
A critical finding was that the association was strongest when acetaminophen was used for prolonged periods, specifically for four weeks or longer during pregnancy.
Despite the observed association, the researchers emphasized the importance of a balanced approach. They noted that acetaminophen remains a crucial medication for managing fever and significant pain in pregnancy, conditions that can themselves pose risks to the developing fetus, such as neural tube defects and preterm birth.
The researchers recommended "judicious acetaminophen use—lowest effective dose, shortest duration—under medical guidance, tailored to individual risk-benefit assessments, rather than a broad limitation."
FDA Response and Expert Commentary
Aligning with these findings, the U.S. Food and Drug Administration (FDA) announced in late September that it would issue a communication to healthcare clinicians, urging caution regarding the use of acetaminophen during pregnancy. Dean Baccarelli confirmed that he had discussed the study's results with Health and Human Services Secretary Robert F. Kennedy Jr. prior to the FDA's announcement, providing a statement that his research found "evidence of an association" between prenatal acetaminophen exposure and NDDs.
The statement continued, "Further research is needed to confirm the association and determine causality, but based on existing evidence, I believe that caution about acetaminophen use during pregnancy—especially heavy or prolonged use—is warranted."
The study was conducted in collaboration with the University of California, Los Angeles, and the University of Massachusetts Lowell. Funding was provided by the National Institutes of Health.