Is acetaminophen taken during pregnancy associated with ADHD?

Readers have contacted me about a recent study that links acetaminophen use in pregnancy to the later development of ADHD in children. Is Tylenol yet another thing pregnant women need to avoid?

The study, titled “Acetaminophen use during pregnancy, behavioral problems, and hyperkinetic disorders” was published this month in JAMA Pediatrics. Dutch researchers looked at about 60,000 children born from 1996-2002. Their parents have been filling out questionnaires and completing phone interviews from pregnancy onward about medication use, illnesses, and many environmental exposures. This study looked specifically at reports of whether mom took acetaminophen during pregnancy, based on multiple phone interviews during pregnancy and six months after each child was born. They also asked about mom’s health during the pregnancy, and about a possible family history of mental disorders. Then, the researches used multiple ways to determine whether these children had ADHD or ADHD-like symptoms at age 7. Parents completed a structured developmental screening tool, and ADHD diagnoses were further collaborated by mining the Danish Psychiatric Central Registry. They also looked at which children had ever filled prescription for a medicine typically used to treat ADHD.

They found that acetaminophen use during pregnancy was correlated with an increased risk all of their ADHD measures — not only the actual diagnosis of ADHD, but ADHD-like behaviors on rating scales and Ritalin prescriptions, too. The risk was increased by 15-40%, depending on the measure; and the risk increased with increasing acetaminophen exposure. Even when the authors factored out the influences of fevers and infections during pregnancy and mom’s mental health, the association remained strong.

So what does this mean? It’s too early to say if acetaminophen caused ADHD. It may be that there was some other factor that drove women to take acetaminophen, such as reduced coping skills or family support. But clearly, there is something going on here, and it is possible that acetaminophen really is the culprit. In this study, 56% of pregnant moms reported taking acetaminophen. Even if the causal factor only increased ADHD risk by a small amount, the net effect would be substantial, given how common acetaminophen use seems to be.

Previous studies have looked at other exposures for pregnant women that might be linked to later ADHD. A 2012 study from New England showed that fish consumption was correlated with a lower risk, and industrial mercury exposure with a higher risk of later ADHD. This study, like the current one, could not prove that these influences were causal, or only associations. But they were statistically valid, and raise important questions about prenatal influences on later mental illness, school, and behavior problems.

If you’re pregnant, I’d think twice about taking any medication, including acetaminophen. While there are times when the risk: Benefit ratio of a medicine is clearly justified, medicines should only be taken when there isn’t a more-safe option. Headaches could perhaps first be treated with massage and relaxation time (which I suspect every pregnant woman deserves anyway). If medicines are used, patients should strive to use the lowest effective dose for the shortest amount of time.

And don’t forget to eat more fish – preferably the kind without any mercury.

Roy Benaroch is a pediatrician who blogs at The Pediatric Insider. He is also the author of Solving Health and Behavioral Problems from Birth through Preschool: A Parent’s Guide and A Guide to Getting the Best Health Care for Your Child.

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