The Center has been closely following the issue of acetaminophen use during pregnancy and concerns that it might cause babies to develop autism and ADHD later in life.

Most of these concerns are the result of a Consensus Statement published in 2021 by a group of scientists in Nature Endocrinology, who claimed that exposure to the commonly used pain killer and fever reducer, “might alter fetal development, which could in turn increase the risks of certain neurodevelopmental reproductive and urogenital disorders [including Autism Spectrum Disorders and ADHD].”

As we’ve noted in previous blog posts, 126 additional scientists and 16 organizations disagreed, and published three rebuttals in the same journal.

One might wonder, what has been the result of all of this controversy to date:

Has the FDA issued new guidelines on the use of acetaminophen during pregnancy?

Has the American College of Obstetrics and Gynecology advised women not to take it?

Did the original group of 91 scientists who signed the Consensus Statement suggest something different from the existing guidelines to help women make good health decisions or reduce the incidence of autism spectrum disorders and ADHD?

The answer to each of the above questions is a resounding “No.”

Instead, there has been an explosion of court cases—more than 500 in a federal MDL (multi-district litigation) and more being developed at the state level. Through national advertising costing millions of dollars, class-action law firms are recruiting parents of children diagnosed with these disorders to sue the makers of Tylenol and generic forms of acetaminophen—and pharmacies such as Walmart, CVS, and Walgreens—for not warning them of possible harms from taking the drug during pregnancy.

The rush to the courtroom, rather than a rush to the lab for more research and evidence, is a troubling response to the uncertainty surrounding this issue. Even so, it is encouraging to see how the MDL federal case has moved forward. In December, U.S. District Judge Denise Cote, in a ‘Daubert hearing’ on the case, decided that the science presented by the Plaintiffs’ attorneys was not reliable enough to support the claims of harm that were being made.

“The unstructured approach adopted by the plaintiffs’ experts permitted cherry-picking, allowed a results-driven analysis, and obscured the complexities, inconsistencies, and weaknesses in the underlying data,” she wrote, as she ruled the evidence inadmissible.

While this decision likely ends the federal MDL case, there are many others at the state level that will probably move forward. It remains to be seen if strong science continues to make a significant difference.

The Center for Truth in Science believes there is still too much unknown about the effects of taking acetaminophen during pregnancy to make any causal claims. To clarify what we know (and don’t know) on this issue, we are seeking applications from independent researchers to conduct a state-of-the-science systematic review to assess the quality of existing studies and identify important gaps in current knowledge.

We issued a request for proposals in December 2023, and we’re accepting applications until March 1, 2024.

We are encouraging teams of scientists with experience in conducting systematic reviews, and expertise or access to expertise in toxicology, epidemiology, child development, and maternal and child health, to apply.

The review must be conducted in as transparent a manner as possible, including protocol registration on a public site. For more details, please click here.

It is important that the best available science be used to make decisions on product liability claims, especially when such products supply important health benefits.

Should Walmart be held at fault, for example, when the FDA does not think the research at this stage supports a relevant relationship between acetaminophen use and increased risk of ADHD and autism, and does not require a warning on the label for use during pregnancy?

And, while considering the risks and benefits of using fever reducers during pregnancy, should we also consider the already known cases of autism and ADHD reported in children who were in utero while their mothers experienced high fevers? Several studies have explored the issue:

  1. Hornig et al., 2017
  2. Croen et al., 2019
  3. Leshtsinski et al., 2022
  4. Gustavson et al., 2019  
  5. Ayubi and Monsori, 2022

These are certainly difficult questions that need robust scientific input to determine the best policy. It appears that Judge Cote agrees. We do too.