The administration recently issued a statement referencing research papers to support claims that Tylenol use during pregnancy leads to autism, but medical experts describe the findings as “limited” and “uncertain”.
Press Release Creates Impression of Additional Support
As stated by Jeffrey Singer, the official statement creates the illusion of extra evidence by citing the same studies multiple times.
For example, a study published this August by Harvard and Mount Sinai is made to look like independent research efforts, and a Boston Birth Cohort study is also cited two times.
“So you say a research from Harvard found the same thing as the Hopkins study and the Mount Sinai study. It can give the impression that the same results have been obtained in multiple studies, all from very prestigious centers,” Singer said.
Correlation vs Cause: Key Distinction
Jake Scott stated that the press release is deeply troubling”, because it confuses correlation with cause”.
There is a much higher bar for establishing cause than association. Proving causation would mean demonstrating that eliminating exposure to Tylenol would decrease the autism incidence.
For example, rising ice cream sales might be associated with heat-related illness, only because both occur in the summer, but banning the sale of ice cream would not reduce the heat stroke cases.
Studies Acknowledge Shortcomings
Not one paper cited by the press release claim to have proven cause. In fact, all of them acknowledge they cannot conclusively prove causation, although some use more cautious wording than others.
A method to rapidly identify the scope of a study’s claims is to search for key terms like “causal”, “cause and effect”, “correlation”, “limitations”, “warning”, and “further investigation”.
Physiological Processes Assertion Doesn’t Hold Up
Once you actually start reading the studies, additional claims in the press release begin to unravel, experts said.
For instance, the statement claims that researchers have suggested physiological processes linking prenatal acetaminophen exposure to changes in brain growth.
But the study linked to illustrate a physiological process fails to provide one. Instead, the researchers state: “Mechanisms underlying the associations are not understood.”
Omitted Research and Other Influences
A further method to fact check the research assertions is to look at what studies are omitted.
As an instance, the press release left out a research from Sweden published in 2024 that tracked nearly two and a half million births and compared siblings.
Singer explained that the association disappears when comparing siblings, who have many more genetic and environmental similarities than comparison groups in other studies.
It indicates that associations observed in other models may have been due to other factors,” the authors wrote.
Habit of Using Poor Research
Singer and Scott concur that the Tylenol claims are reminiscent of arguments against vaccines.
Scott said that it follows a trend of using poor-quality research based on flawed scientific papers.
“It’s all part of a pattern of exploiting really weak evidence that’s based on really poor quality studies,” Scott said.
In summary, medical experts warn that the research connecting Tylenol to autism is not definitive and urge more studies before drawing firm conclusions.
