Acetaminophen, the pain-relieving drug found in Tylenol, has been linked to ADHD in children if taken during pregnancy.

A new study published in the journal JAMA Pediatrics found a correlation between using acetaminophen while pregnant and later behavioral problems for the child, Forbes reported.

The authors note that causation can't be determined yet, so it's too early to make recommendations. But pregnant women should take a look at the study and talk to their doctors about whether or not to take acetaminophen.

Researchers kept track of more than 64,000 children and mothers in the Danish National Birth Cohort, Forbes reported. Of the women in the study, slightly more than half used acetaminophen while pregnant.

For the study, the mothers answered questions about acetaminophen intake during pregnancy as well as queries about their children's behavior. The study tracked official diagnoses of hyperkinetic disorder, which is a severe form of ADHD, and prescriptions for ADHD medications like Ritalin.

"When women reported having used acetaminophen for 20 or more weeks during pregnancy, the risk for HKD diagnosis in children almost doubled," the study's authors wrote.

Acetaminophen use during pregnancy was "strongly linked" to a higher risk of ADHD in the child's first seven years, an increase of some 30 percent. Mothers who took the drug more frequently had children with a higher risk of behavioral issues.

According to the authors, it's "possible that acetaminophen may interrupt brain development by interfering with maternal hormones or via neurotoxicity such as the induction of oxidative stress that can cause neuronal death."

The drug, which is a hormone disrupter, can cross the placenta, affecting the fetus and its developing nervous system.

The study was inconclusive, the authors noting that other factors could be at play. While it's too early to advise mothers to avoid Tylenol, if further study confirms the causation, "acetaminophen should no longer be considered a safe drug for use in pregnancy," the authors said. 

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