Study: Acetaminophen During Pregnancy Raises Risk for ADHD

A mother’s use of the most common over-the-counter pain reliever and fever reducer during pregnancy may increase her child’s risk of attention deficit hyperactivity disorder, or ADHD, according to study published Monday.

The study, published in the American Medical Association’s journal Pediatrics, examined the effects of a pregnant mother’s use of acetaminophen on their children's behavior.

Preliminary results showed an increased risk for ADHD-like behaviors in children at 7 years old if their mothers had taken acetaminophen while pregnant.

An estimated 6.4 million children—11 percent of those ages four to 17—were diagnosed with ADHD in 2011. In 2003, 7.8 percent of children had ADHD, according to the U.S. Centers for Disease Control and Prevention (CDC).

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Studying Acetaminophen Use in Pregnant Women

Researchers at the University of California, Los Angeles (UCLA) and other institutions report that mothers who used acetaminophen, the main ingredient in the majority of Tylenol’s products, for example, were at a higher risk of having children with ADHD behaviors, as well as hyperkinetic disorder (HKD), a particularly severe form of ADHD.

Researchers examined 64,322 children in the Danish National Birth Cohort to examine the effects of acetaminophen use on a developing fetus. More than half of pregnant women in Denmark and the U.S. report using acetaminophen during pregnancy, according to the study’s background. 

Recent studies in both animals and humans suggest that acetaminophen can disrupt a person’s endocrine system and prenatal exposure may cause behavioral dysfunction by interfering with sex hormones.

In surveys during and after pregnancy, women reported their use of various pain relievers and, later, the behavioral traits of their children, including whether ADHD had been diagnosed by age 7.

Researchers say that for mothers who reported using acetaminophen for 20 or more weeks during pregnancy, the risk of having a child with HKD almost doubled, and the risk of being medicated for ADHD increased by 50 percent.

The study suggested that the widespread use of acetaminophen may explain for the rising incidence of HKD and ADHD, but further studies are needed to verify these findings.

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The Medical Jury Is Still Out

While researchers say their preliminary findings warrant more research, it’s an interesting look at how the disorder’s prevalence continues to rise in developed countries.

In an editorial accompanying the research, Miriam Cooper of Cardiff University School of Medicine, Wales, wrote that findings from the study should be interpreted cautiously and should not change practice.

“However, they underline the importance of not taking a drug’s safety during pregnancy for granted, and they provide a platform from which to conduct further related analyses exploring a potential relationship between acetaminophen use and altered neurodevelopment,” the editorial concludes. 

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