(NewsNation) — President Donald Trump is set to make an announcement about autism on Monday that is expected to include a recommendation that pregnant women refrain from using Tylenol unless they have a high fever, a source tells NewsNation.

Tylenol, whose active ingredient is acetaminophen, is a common pain reliever that doctors have long considered safe to use during pregnancy.

The Trump administration is expected to say that using Tylenol during pregnancy could contribute to autism risk, the White House source said. However, leading maternal and prenatal care organizations have pushed back against the anticipated claim, which was first reported earlier this month.

Watch the press conference in the player above at 4 p.m. Eastern time.

“Acetaminophen remains a safe, trusted option for pain relief during pregnancy,” the American College of Obstetricians and Gynecologists said in a Sept. 5 statement.

The ACOG said there’s “no clear evidence” linking “prudent Tylenol use” to issues with fetal development and said it’s safe to use in moderation. Still, pregnant women should consult with their doctors, as with all medicines.

Monday’s announcement comes after Health Secretary Robert F. Kennedy Jr. pledged to find the causes of autism by September — a goal researchers see as unlikely to be achieved.

“There’s no way, that in two months, they’ve sorted out what the cause of autism is,” Dr. Anahita Dua, assistant professor at Harvard Medical School, told NewsNation on Saturday.

What research is already out there on autism and pregnancy?

After years of research, scientists haven’t identified a single cause of autism, but a mix of factors appears to raise the risk, according to the Centers for Disease Control and Prevention.

Those include environmental, biological and genetic influences. For example, a child may be more likely to develop autism if they’re born to older parents, have a sibling with the condition, carry certain genetic or chromosomal traits or experience complications at birth, the CDC says.

“It’s very unlikely that we’re going to find one cause that’s causing all of the autism,” former CDC director Dr. Tom Frieden told NewsNation earlier this month, noting that the condition exists on a spectrum.

Notably, childhood vaccines “do not cause autism,” and maternal vaccines have not been shown to cause autism, according to the Institute for Vaccine Safety at Johns Hopkins University.

As for acetaminophen, Frieden said the latest report is not based on new data but rather a new analysis of existing studies, and it suggests there “may be a role for Tylenol in some people who develop autism” but cautioned that the evidence is “far from definitive.”

Dr. Anita Patel, a pediatric critical care specialist, worries the Trump administration’s warning about Tylenol could backfire if it leads pregnant women to avoid the medication altogether.

“Uncontrolled fevers during pregnancy absolutely can cause harm,” Patel told NewsNation on Sunday.

Frieden echoed that concern, calling it a “really tough problem” because other painkillers are “definitely not safe during different parts of pregnancy.” He urged women to consult with their doctors.

Why are autism diagnoses on the rise?

Autism diagnoses have increased over the years, a challenge Kennedy has called an “epidemic,” but the reasons are complicated.

According to the CDC’s latest report, about 1 in 31 (3.2%) 8-year-old children were identified with autism across the Autism and Developmental Disabilities Monitoring network’s 16 sites. That’s up from the previous estimate of 1 in 36 as recently as 2020 and 1 in 150 in 2000.

Put another way: That’s a roughly 300% increase in autism diagnoses over the past 20 years or so.

Researchers largely attribute the rise to two main factors: a broader definition of Autism Spectrum Disorder and more widespread screening.

In other words, more people are meeting today’s definition of autism than previously, and parents and doctors have become more aware of the early warning signs.

Still, the steady increase has researchers asking whether broader societal changes might also be playing a role — a question that remains under study. One known factor: The average age of mothers at childbirth has risen, and older parental age is one of the most consistently identified risk factors for autism.

One major study published last year detected a small association between prenatal acetaminophen use and autism, but that link disappeared in sibling comparisons, suggesting other factors, not the drug, may be driving the marginal increase in risk.

“We never want to assume that just because two things are correlated that one causes the other,” Dr. Krupa Playforth, a board-certified pediatrician, told NewsNation on Monday.

In a separate study, researchers analyzed results from 46 previous studies and found that when children are exposed to acetaminophen during pregnancy, they may be more likely to develop neurodevelopmental disorders, including autism and ADHD.

Rather than recommend a “broad limitation,” the researchers suggested “judicious acetaminophen use,” meaning the lowest effective dose for the shortest duration.

OB-GYN recommendations for pregnant women

Dr. Jamil Abdur-Rahman, a board-certified obstetrician and gynecologist in Chicago, is concerned that Monday’s expected Tylenol announcement could make patients hesitant to use one of the only safe pain medications for pregnancy.

“Tylenol is really one of the only go-to options that we have,” Abdur-Rahman said ahead of Trump’s announcement. “It can really be important to reduce fevers in pregnancy.”

Like others, he worries that Tylenol-skepticism could cause some to endure fevers unnecessarily or turn to unsafe non-steroidal anti-inflammatory drugs like ibuprofen.

“If there’s even a hint that there could be an issue, I think that they will avoid [Tylenol], and that too could lead to a lot of issues,” Abdur-Rahman said.

So long as the ACOG says Tylenol is still safe to use, Abdur-Rahman said he would feel comfortable recommending it.

Dr. Patel agreed and doesn’t think pregnant women need to pause before taking Tylenol, but said that everyone should discuss any medication they take with their doctors.

The Society for Maternal-Fetal Medicine has also said pregnant women can use acetaminophen when pain and fever relief are needed after consulting with their doctor.

“At this time, the weight of scientific evidence that acetaminophen use during pregnancy causes an increased risk for autism or ADHD is simply inconclusive,” Dr. Sindhu Srinivas, an OB/GYN, said in a statement earlier this month.