Acetaminophen Use During Pregnancy Linked to ADHD Risk in Kids

Children whose mothers used acetaminophen during pregnancy had an increased risk for behavioral problems related to ADHD, but experts advise that more research is required to investigate the association.

Although acetaminophen is considered to be safe for use by pregnant women, new research suggests that fetal exposure to the medication may increase the risk for behavioral problems related to attention-deficit/hyperactivity disorder (ADHD) in children.

Previous research has suggested that acetaminophen, the most commonly used medication for pain and fever during pregnancy, has endocrine-disrupting properties that could affect fetal brain development. To investigate the nature of these potential effects, the current study, published online on February 24, 2014, in JAMA Pediatrics, assessed the association between maternal use of acetaminophen during pregnancy and the risk for developing ADHD-like behaviors, being diagnosed with hyperkinetic disorders (HKDs), or using ADHD medications in children who were enrolled in the Danish National Birth Cohort from 1996 through 2002.

Mothers reported their use of acetaminophen in 2 telephone interviews during pregnancy and an additional interview 6 months after giving birth. When a participating child reached age 7, the child’s mother or another caregiver completed the Strengths and Difficulties Questionnaire to assess ADHD-like behaviors. Children who were diagnosed with an HKD at age 5 years or older and those who filled 2 or more prescriptions for ADHD medications were identified through national registries.

More than half (56%) of all women included in the study reported using acetaminophen during pregnancy. The results indicated that children who were exposed to acetaminophen while in the womb were at increased risk of being diagnosed with an HKD (hazard ratio 1.37), using ADHD medications (hazard ratio 1.29), or having ADHD-like behaviors at age 7 (risk ratio 1.13) compared with those who had not been exposed to the medication.

These risks were even greater when women increased their use of the medication throughout their pregnancy or when they reported taking it in more than 1 trimester. When women reported using acetaminophen for 20 or more weeks during pregnancy, the risk of HKD diagnosis in children nearly doubled (hazard ratio 1.84) and the risk for taking ADHD medications increased by 50%. The relationship between prenatal acetaminophen exposure and risk for all outcomes did not significantly change when possible confounders, including maternal inflammation and infection during pregnancy and maternal mental health problems, were accounted for.

Although the study’s results may seem alarming, the authors of an accompanying editorial note that the findings do not prove a cause-and-effect relationship and should be interpreted with caution. Considering the common use of acetaminophen during pregnancy and the large number of children diagnosed with ADHD, they suggest that additional studies are needed to expand on the evidence and further investigate the association.

“[The study’s findings] 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 editorialists conclude.