While media coverage of studies suggest that acetaminophen use in pregnancy may be associated with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD) in children, the overwhelming body of evidence suggests there is no known association.

“The studies suggesting an association do not account for other important facts such as increased risk of these disorders within families, which is likely a result of genetic difference or differences in environment,” Metz explains.

Other significant flaws in the studies demonstrating an association include:

• Self-reporting has the potential for recall bias. When you receive an upsetting diagnosis about your child, it’s easy to immediately start thinking about things you did during pregnancy to pinpoint a cause. You might be more likely to recall taking acetaminophen during pregnancy if you have a child with ASD or ADHD, especially if you are primed to believe there is a relationship there. Similarly, you are less likely to recall it if you don’t have an affected child.
• The reason for taking acetaminophen might be the true risk factor. Studies have failed to consider why people were using acetaminophen during pregnancy. Acetaminophen is often used to treat fever or inflammation. Fevers can be a symptom of an underlying viral or bacterial infection. Infection or inflammation, not the treatment, could be what is actually associated with ASD or ADHD.
• Diagnosis of neurobehavioral disorders continue to evolve. According to the Society for Maternal-Fetal Medicine, the causes of disorders like ASD and ADHD are unknown, and there is the potential for other contributing factors that are not measured in these studies, such as genetic predisposition.