Whopper of the Week: RFK Jr. Blames Tylenol Taken in Pregnancy for Autism

THIS WEEK'S WHOPPER: 

RFK Jr. Gets the Science Wrong Again, Blaming Tylenol Taken In pregnancy for Autism

SUMMARY:
 

Acetaminophen, also known as Tylenol, is widely regarded as safe to take during pregnancy. Numerous well-designed studies have repeatedly demonstrated the safety of acetaminophen use during pregnancy.  But Secretary Kennedy is once again not understanding the science. On September 23, 2025, at a press conference to reveal the supposed causes of autism, Donald Trump, with Robert F. Kennedy Jr. behind him, claimed that acetaminophen should not be taken by women during pregnancy, alleging it may contribute to increasing rates of autism and neurodevelopmental disorders in children. Acetaminophen’s safety during pregnancy has been examined and the most robust studies consistently show it is safe to use as directed. Despite the weight of the evidence, Secretary Kennedy is wielding his power recklessly, with plans for the FDA to issue a black-box warning for acetaminophen use in pregnancy.  If acetaminophen were unnecessarily removed as an option for pregnant women, that would not reduce autism incidence. Instead, women would be left with no safe alternative treatment for fevers, which could harm their unborn children, since uncontrolled fevers can lead to miscarriages, birth defects, and neurodevelopmental disorders.

WHY IS THIS A WHOPPER?

Autism is a complex neurodevelopmental condition that has been extensively studied for decades. There is no single cause of autism, although by far the biggest risk factor is genetics. Autism is highly heritable. Genes explain about 50-80% of the differences in who develops autism in a population. Scientists are exploring what sorts of environmental exposures also increase the risks of developing autism and what interventions could mitigate the severity of symptoms. Over the last decade there has been a discussion about the meaning of an association that some studies find and others do not, between acetaminophen (e.g. Tylenol) use during pregnancy and neurodevelopmental disorders such as autism. The risks attributed to acetaminophen are inconclusive, small and in the gold-standard studies nonexistent.

RFK Jr.’s strong support of the FDA’s new warning about acetaminophen use in pregnancy is based on a recent meta-analysis, published in August of 2025, that has been criticized as flawed and does not represent the consensus position in medicine about the safety of acetaminophen or the causes of autism. The American College of Obstetrics and Gynecology (ACOG), the American Academy of Pediatrics (AAP), the International Federation of Gynecology and Obstetrics (IFGO), the World Health Organization (WHO), and numerous health agencies from around the world have issued statements that there is no conclusive evidence that using acetaminophen as directed causes autism or other neurodevelopmental disorders.

The medical consensus about the safety of acetaminophen use during pregnancy is based on numerous lines of robust evidence.  The largest study to examine this question included 2.5 million children in Sweden. It found no link between the use of  acetaminophen during a mother’s pregnancy and the development of neurodevelopmental disorders including autism in her children. This study compared different pregnancies of the same mother and recorded acetaminophen use in each of them, so they could compare siblings who were or were not exposed to acetaminophen and at what doses. The use of sibling controls reduces confounding effects of genetics and the environment and helps to isolate the effect of acetaminophen on pregnancy outcomes. When you compare siblings, the acetaminophen-autism link "completely disappeared.” Further, children exposed to higher doses of acetaminophen did not have higher risks of neurodevelopmental disorders. Other studies, including one in Japan, have confirmed that when familial confounding is properly controlled, there is no increased risk of autism due to acetaminophen use.

While studies have shown genetics accounts for the majority of the variability in the development of autism, environmental factors still play a role. The highest risks are associated with prematurity at birth, cerebellar injury, maternal and paternal age at conception, and maternal infections during pregnancy, in particular rubella infections. Researchers are also looking at a variety of risks associated with medications, nutrition, air pollution and environmental contaminants. Some factors, like Cesarean deliveries, may indeed be modifiable. None are likely to be the singular cause of autism or easily eliminated. 

WHY IT MATTERS?

By changing the FDA labeling and cautioning women to consult with their healthcare provider before taking acetaminophen during pregnancy, RFK Jr. causes unwarranted confusion and unnecessary worry over the safety of acetaminophen for fever or pain in pregnancy. 

Acetaminophen is safe to take during pregnancy at recommended doses for fever or pain. A majority of women take the drug  at some point in their pregnancy. There are no other safe alternatives for pregnant women other than acetaminophen. Non-steroidal anti-inflammatory drugs, or NSAIDs (such as aspirin), used for pain or fever during pregnancy can cause miscarriage, birth defects, low amniotic fluid and should not be taken during pregnancy.  Letting high fevers go untreated can also lead to birth defects, neurodevelopmental disorders and miscarriages. Not having safe alternatives for pregnant women to take for pain is cruel.

This FDA decision will also pave the way for more litigation against the makers of acetaminophen. Two years ago a judge dismissed five hundred cases where litigants accused Kenvue, the maker of acetaminophen, of not properly informing users of the supposed autism link. Now that the FDA has put out a black-box warning, families are appealing the dismissal of this case and asking the judge to consider the new federal guidance. For trial lawyers, and consultants to law firms like Secretary Kennedy previously was, this could mean more damage awards and settlements for years to come.

Contributors to this post are:  Miriam Rabkin, MD, MPH, Aurora Horstkamp, MD, Benedicte Callan, PhD, Jackie Goldenberg, BA.