They’re prominent talking points for Health Secretary Robert F. Kennedy Jr. and his top officials: Taking Tylenol while pregnant could be linked to autism. Antidepressants may be harmful during pregnancy. Aluminum salts in vaccines might pose a health risk. And Covid shots don’t benefit healthy children.
The remarks have sowed confusion over the past year, as scientists warn there isn’t evidence to back them up. Nevertheless, federal health agencies have pursued policies based on the assertions.
Now, a spate of new research released in the last few months offers some of the strongest rebuttals to date.
The latest finding came this month: After Food and Drug Administration officials questioned the safety of taking antidepressants during pregnancy, new research presented at an annual meeting of the Society for Maternal-Fetal Medicine found that pregnant patients who discontinued the medications nearly doubled their risk of mental health-related emergency room visits.
Other recent studies have also found that aluminum salts in vaccines aren’t linked to major safety concerns and that Covid shots have a protective benefit for children.
Some papers were initiated in response to statements from Kennedy and the White House, while others had already been underway.
“These are just the latest examples in a record that stretches back a decade of Secretary Kennedy making claims about vaccines that are contradicted by facts and data,” Michael Osterholm, executive director of the University of Minnesota’s Vaccine Integrity Project, said in a statement. The project was started after Kennedy’s confirmation to create an independent, transparent process for evaluating vaccine safety, he said.
Emily Hilliard, a spokesperson for the Health and Human Services Department, said in a statement that “HHS remains focused on rigorous scientific review, transparency, and ensuring the continued safety and effectiveness of the U.S. vaccine supply.”
The Trump administration has pledged to conduct its own “gold standard” studies of vaccine safety and the causes of autism, among other topics of interest to Kennedy. But those studies haven’t yet come — and many public health experts question whether they will be free of bias when they do. (Decades of studies have debunked the link between vaccines and autism.)
Already, some of the administration’s high-profile claims about drugs and vaccines have become the official stances of federal health agencies: The Centers for Disease Control and Prevention stopped recommending Covid shots for healthy children last year, and in September, with Kennedy standing behind him, President Donald Trump told pregnant women to “fight like hell” not to take Tylenol.
What’s safe to take while pregnant?
In the past year, several top health officials have warned of potential harms from taking Tylenol and antidepressants while pregnant. But the latest evidence released since January doesn’t substantiate those concerns.
The FDA convened a panel in July in which nearly all the panelists raised concerns about pregnant women taking selective serotonin reuptake inhibitors — a class of antidepressants that includes Lexapro, Prozac and Zoloft. The stance went against the American College of Obstetricians and Gynecologists’ recommendation that pregnant patients stay on the medications. Psychiatrists widely criticized the event.
The FDA commissioner, Dr. Marty Makary, said during the panel that SSRIs may lead to birth defects and questioned their effectiveness, claiming that “the more antidepressants we prescribe, the more depression there is.” Some panelists also called for stronger warnings on SSRI drug labels.
Hilliard told NBC News that “the FDA will thoroughly review the data and update products labels as appropriate” if high-quality research shows safety concerns beyond what is mentioned on the labels.
SSRI labels currently refer to a potential increased risk of excessive bleeding known as postpartum hemorrhage in the mother or a life-threatening breathing issue called persistent pulmonary hypertension in the newborn. However, evidence suggests that those risks are minimal, especially when they are compared with the risks of depression itself.
“In general, we don’t think of it as being so risky that we would ever recommend a patient stop their medication because of it,” said Dr. Kelly Zafman, a maternal-fetal medicine fellow at the Hospital of the University of Pennsylvania.
On its own, untreated depression can elevate the risk of preterm birth and pre-eclampsia. Scientists also haven’t found strong evidence that SSRIs are linked to autism or birth defects.
Zafman presented fresh research this month that analyzed health insurance claims of nearly 4,000 patients with depression or anxiety who took antidepressants before their pregnancies. Among women who discontinued the antidepressants in pregnancy, 1,357 had mental health-related ER visits, compared with 795 who stayed on their prescriptions.
Zafman said some of the ER visits could be related to overdoses, suicide attempts or debilitating insomnia, though the insurance data didn’t specify the type of mental health emergency. Many of those issues can be life-threatening to a fetus.
A more common drug sometimes taken during pregnancy, Tylenol, also doesn’t bring the dangers that Trump and Kennedy have described.
The two warned in September about a potential link between Tylenol in pregnancy and autism in children. Makary also told physicians in a written notice to “consider minimizing the use of acetaminophen,” the active ingredient in Tylenol.
Hilliard, the HHS spokesperson, said many experts have expressed concern about using acetaminophen during pregnancy. However, robust scientific evidence doesn’t support the claim. Kenvue, the maker of Tylenol, has said research shows acetaminophen doesn’t cause autism, and it has urged U.S. regulators not to put an autism warning label on the medication.
A group of researchers tried to clear up the confusion last month by publishing one of the most thorough analyses on the subject. The team excluded studies with evidence of bias, such as those that didn’t follow study participants for very long or disclose pregnant women’s health histories. They found no link between the use of acetaminophen in pregnancy and neurodevelopmental disorders, including autism.
“We know autism is this complex interplay between hundreds of genes and environmental factors early on in pregnancy,” said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Texas and a co-director of the Texas Children’s Hospital Center for Vaccine Development.
Certain chemical exposures early in pregnancy can interact with autism genes, Hotez said, but that Kennedy “has no interest in actually evaluating those.”
Vaccines: Supposed risks and demonstrated benefits
In September, the CDC formally changed its Covid vaccine guidance to recommend that people decide with their doctors whether to get the shots. Months earlier, Kennedy, Makary and Dr. Jay Bhattacharya, director of the National Institutes of Health, said the agency would no longer recommend Covid shots for healthy children and pregnant women.
In a video on X announcing the change, the officials claimed there was no evidence to support giving children Covid boosters. The FDA’s top vaccine regulator, Dr. Vinay Prasad, also told staff members in a memo last fall that Covid shots killed at least 10 children — but didn’t provide evidence, such as documentation of the deaths, to support the claim.
The CDC’s own research has consistently found that Covid vaccines and booster shots protect against severe illness in children. Most recently, a CDC study in December found that the Covid vaccines given from 2024 to 2025 reduced the risk of Covid-related emergency room and urgent care visits by 76% among children ages 9 months to 4 years and by 56% among children ages 5 to 17.
Kennedy, who has a history of anti-vaccine activism, referred to the Covid vaccine in 2021 as “the deadliest vaccine ever made.” In June, he fired the previous members of the CDC’s vaccine advisory panel and replaced them with a group largely skeptical of Covid shots.
Under his leadership, HHS is investigating whether aluminum salts in vaccines could be linked to autism, according to a statement posted on the CDC website in November. Trump said at a news briefing last year that aluminum was being “taken out of the vaccines,” adding: “Who the hell wants that pumped into a body?”
Aluminum salts — which are naturally present in soil and water — are added to vaccines to boost the body’s immune response, allowing a smaller dose to be used. Nearly a century of evidence has found them to be safe for that purpose. Many childhood vaccines in the U.S. contain aluminum salts, including those for hepatitis A and B, HPV, meningitis and whooping cough.
However, aluminum salts have been a target of many anti-vaccine activists. Kennedy told food blogger Mikhaila Peterson in 2021 that the brains of children with autism were “loaded with aluminum.”
A December analysis in the journal Pediatrics reviewed the existing evidence in light of mounting vaccine hesitancy. The researchers didn’t detect any major safety concerns linked to aluminum salts in vaccines.
“This is sort of Kennedy’s playbook. He’s never followed the science,” Hotez said. “You can throw all the evidence you want at him and he’s oblivious to it. It’s all about him cherry-picking whatever he thinks supports his agenda.”
