Use of Tylenol during pregnancy does not cause autism, experts say
National obstetric guidance reaffirms that acetaminophen, or Tylenol, is the safest option for treating fever and pain during pregnancy and finds research showing an increased risk of autism or ADHD “inconclusive.”
The occasional use of acetaminophen during pregnancy to treat a headache or fever is safe and will not cause autism or other neurodevelopmental disorders, say two Northeastern University health care experts.
“If you take two 500 milligrams of Tylenol one or two times during your pregnancy, that is simply not enough to cause epigenetic damage,” says Elyse Watkins, an associate clinical professor with expertise in obstetrics and gynecology, and the associate director of the university’s Doctor of Medical Science in Healthcare Leadership program. “Ending up with a high fever is way more harmful than 1,000 milligrams of Tylenol.”
Watkins was responding to a report from President Donald Trump and Robert F. Kennedy, the U.S. secretary of Health and Human Services, citing Tylenol use and folate (vitamin B9) deficiency as potential causes of autism.
The Society for Maternal-Fetal Medicine reaffirmed its recommendation that acetaminophen is an appropriate medication to treat pain and fever during pregnancy, stating that untreated fever, particularly in the first trimester, increases the risk of miscarriage, birth defects and premature birth.
“At this time, the weight of scientific evidence that acetaminophen use during pregnancy causes an increased risk for autism or ADHD is simply inconclusive,” SMFM President Sindhu K. Srinivas, MD says in a statement. “In maternal-fetal medicine, as in all of medicine, our recommendations are based on an evaluation of rigorous research and data, clinical expertise, and our patients’ values and preferences.”
It is important to consider when, during pregnancy, a woman uses acetaminophen, says
Megan Woodbury, a postdoctoral research associate at Northeastern’s PROTECT Research Center. Woodbury researched the safety of using acetaminophen during pregnancy in 2023.
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Using data collected from 532 pregnant women who participated in the Illinois Kids Development Study between December 2013 and March 2020, they measured acetaminophen use at six points during pregnancy — approximately every four to six weeks. The women’s children were then evaluated for language skills when they were around 2 years old and later at 3. That data was compared to data from peers.
Woodbury and colleagues at the University of Illinois found no association between acetaminophen use in the first trimester and delayed language development. However, increased use during the second trimester was related to lower language scores at age 3 and smaller vocabulary size at age 2.
Language development is often impaired in conditions like autism, but Woodbury cautions against considering her findings as evidence of a direct link between acetaminophen use and autism.
The research was published in the journal Pediatric Research.
“The changes we saw were very, very small,” she says. “Our findings are only correlational, so we can’t say acetaminophen definitely caused these relationships. There are other factors we may not have considered.”
Watkins says that acetaminophen, the active ingredient in Tylenol, is the only safe medication for pregnant women to take to address fevers. In addition, triptans, a class of medication commonly prescribed to treat migraine headaches, are not considered safe, she says. Women experiencing migraine headaches during pregnancy are advised to use acetaminophen instead, she says.
Watkins questioned the federal report on Tylenol. Scientific consensus holds that autism is caused by a combination of genetic and environmental factors, Watkins says. Other environmental factors that have been identified as potential risk factors for autism spectrum disorders, including microplastics, but the federal agency has only singled out acetaminophen.
However, a study led by the Icahn School of Medicine at Mount Sinai published in August concluded that children are more likely to develop neurodevelopmental disorders (NDDs), including autism and ADHD, when exposed to acetaminophen during pregnancy.
That research states that “numerous well-designed studies have indicated that pregnant mothers exposed to acetaminophen have children diagnosed with neurodevelopmental disorders.”
One of the study’s authors, Watkins notes, disclosed in the research paper that he served as an expert witness in a case related to general causation involving acetaminophen use during pregnancy and its potential links to neurodevelopmental disorders.
“As someone who has practiced in obstetrics and gynecology for decades and having had three children of my own, there are many other variables that we are exposed to,” Watkins says. “I’m highly skeptical.”
Woodbury cites another study published last year of 2 million Swedish children that compared siblings within the same family, where one child was exposed to acetaminophen in the womb and their sibling wasn’t. The study found no risk of autism, ADHD or other intellectual disability.
Woodbury, who used Tylenol during her pregnancy with her daughter in consultation with her doctor, says that after seeing findings from the Swedish study, she more strongly questions a causal connection to autism.
The American College of Obstetricians and Gynecologists (ACOG) also issued a statement affirming its recommendation that acetaminophen is safe to use during pregnancy.
“Pregnant patients should not be frightened away from the many benefits of acetaminophen, which is safe and one of the few options pregnant people have for pain relief,” says Dr. Christopher Zahn, chief of clinical practice.
ACOG has also issued guidance to obstetric care providers to provide pregnant patients with the best available information about pain medications to address their specific health issues.
“If you have any questions about it, go to your health care provider,” she says. “That’s what I would tell my patients. That’s what I would tell my friends and my family.”
