Acetaminophen Use in Pregnancy Does Not Increase Risk of Autism or ADHD, Study Finds

A new study says products with acetaminophen like Tylenol do not increase the risk.

Fact checked by Sarah Scott

Using acetaminophen, which comes in brand names like Tylenol, during pregnancy has been associated with neurodevelopmental disorders, including autism or attention deficit hyperactivity disorder (ADHD). But a large new study conducted in Sweden indicates that acetaminophen may not be linked to these conditions after all. Instead, researchers say other causes, such as genetics, may be at the root.

Published in the JAMA, this study evaluated data from nearly 2.5 million Swedish children who were followed between 1995 and 2021. The researchers compared data on those who were exposed to acetaminophen with those who were not and noted a small risk of autism, ADHD, and intellectual disabilities in the exposed group.

But when they used a sibling analysis—where they compared siblings with the same biological parents—they found there was no evidence that acetaminophen use during pregnancy increased the risk for these disorders.

"Sibling analyses help to control for other family characteristics that aren’t captured well by our data, but that are likely to be similar across pregnancies and throughout the early life of the children," says Brian Lee, PhD, the corresponding author on the study and an associate professor of Epidemiology at Drexel University’s Dornsife School of Public Health. "By comparing siblings born to the same mother, we can control for many indications as well as early life environmental factors that might influence the relationship that we are studying."

Dr. Lee adds, "When we compared the full siblings, we saw no difference in risk between the exposed siblings and the unexposed siblings."

Here's what you need to know about this study and what it might mean for acetaminophen use in pregnancy.

New Findings on Acetaminophen During Pregnancy

Research from this new study contradicts some previous studies, which indicate that acetaminophen use may be connected to neurodevelopmental disorders. "This study is a very important response to concerns from the previous studies," says Karen Keough, MD, a pediatric neurologist and medical director at Pediatrix Medical Group in Austin, Texas, who is not affiliated with the study.

Researchers believe that these past associations may be attributable to confounding. That's a variable that influences the outcome of a study and sometimes even creates a false association.

This current study, which was funded by the National Institute of Neurological Disorders and Stroke (NINDS), is the largest of its kind. This is important, as is the sibling analyses. That allowed researchers to limit the influence of other potential risk factors and to focus specifically on the risks associated with acetaminophen in pregnancy.

One of those is genetics. Dr Lee explains, "Since other studies have shown that women with a higher genetic liability for neurodevelopmental disorders like ADHD are more likely to report taking acetaminophen during pregnancy, as well as to suffer from indications for use of pain-relievers during pregnancy, we felt that it was extremely important to understand this component."

Experts at the National Institutes of Health say that the ability to control for these confounding factors support the conclusion that acetaminophen is not directly linked to an increase risk of ADHD, autism, or intellectual disability.

That said, the study is limited by the fact that it relies on data from prescribed acetaminophen and from self-reporting, which means the researchers may not have captured all acetaminophen use including from other over-the-counter medications. But due to the size of the study, this limitation should have had a minimal impact.

Related: Can Taking Acetaminophen While Pregnant Affect a Child's Speech Development?

So, Is Tylenol Safe During Pregnancy?

While the use of acetaminophen is generally considered safe to use in pregnancy—and is thought to be much safer than the alternatives like aspirin and ibuprofen—a number of experts have advised pregnant people to abstain from using it unless absolutely necessary. Consequently, these recommendations may have caused pregnant people to avoid using the over-the-counter medication, even when it's needed.

As a pain reducer and anti-fever agent, acetaminophen can be important in pregnancy because other pain and fever medications like ibuprofen or naproxen should not be taken, says Dr. Keough. "Fever, in particular, can be dangerous to the developing baby’s brain and should be controlled, especially in early pregnancy, and pain relief might be essential for many situations," explains Dr. Keough.

Even though the current study wasn't geared specifically toward analyzing the safety of acetaminophen during pregnancy, Dr. Lee says the researchers hope that their study provides more information for health care providers to provide advice to their pregnant patients. The results of this study can be particularly useful if pregnant people are worried that their use of acetaminophen has increased fetal risk for neurodevelopmental conditions, he says.

But when you're pregnant, it's always best to consult with your health care provider before taking any medication—including acetaminophen. Not only is there a risk for interactions with your current medications or supplements, but it's also important to consider your particular pregnancy and risk factors.

That said, pregnant people and their families should feel confident that acetaminophen is safe and should not avoid using it when necessary, says Dr. Keough. "It’s best to avoid medications if non-essential, but sometimes it’s important to treat a serious issue even during pregnancy," adds Dr. Keough.

Likewise, Dr. Lee says he and the other researchers hope that expectant parents find the results of their study reassuring—especially if they experience anxiety when suffering from pain or fever during pregnancy. The study results also should help quell some concerns for parents of young children who are visiting the pediatrician with worries about their past acetaminophen use, he says.

Related: 22 Healthy Pregnancy Tips for the Whole 9 Months

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