Acetaminophen use during pregnancy may impair fetal neurodevelopment.

Acetaminophen, a drug used to treat pain and reduce fever, has a generally favorable safety profile and is considered safe for use during pregnancy. However, evidence from studies in rodents and humans suggests that acetaminophen exerts endocrine-disrupting properties, which could alter neurological development. Findings from a 2014 study suggest that children of women who took acetaminophen during pregnancy are more likely to develop attention-deficit/hyperactivity disorder (ADHD)-like behavioral problems or hyperkinetic disorders.

ADHD is a neurobehavioral condition characterized by inattention and/or hyperactive or impulsive behavior that interferes with functioning, learning, or development. The condition affects more than 9 percent of children living in the United States. Hyperkinetic disorders are conditions characterized by abnormal involuntary movements, such as tremors or tics. The disorders affect 1 to 2 percent of people worldwide and are more common among males.

The investigators drew on data from nearly 65,000 children and mothers enrolled in the Danish National Birth Cohort study. They collected information about the mothers' acetaminophen use during pregnancy via phone interviews and identified children with ADHD or hyperkinetic disorders via parental reports, medical records, and prescription records.

They found that more than half of the women reported taking acetaminophen during their pregnancies. Children of the women who took the drug during pregnancy were 13 percent more likely to have ADHD-like behaviors at the age of 7 years; 29 percent more likely to take ADHD medications; and 37 percent more likely to be diagnosed with a hyperkinetic disorder at birth. These findings held true even after considering possible confounders, such as maternal inflammation, infection during pregnancy, the mother’s mental health problems, or others. The investigators noted longer prenatal exposure strengthened the associations between acetaminophen use and neurodevelopmental disorders.

These findings suggest that acetaminophen use during pregnancy influences fetal brain development, potentially increasing the risk of ADHD or hyperkinetic disorders. The investigators posited that if their findings are indicative of causal associations, acetaminophen should no longer be considered safe for use during pregnancy. However, the American College of Obstetrics and Gynecology continues to support the use of acetaminophen during pregnancy.

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