Taking acetaminophen during pregnancy does not cause autism spectrum disorder in children, according to the best-available data, and there are good reasons for moms-to-be to take the drug — also known as Tylenol and paracetamol — for pain and fever.

The pregnancy-related risks associated with medications, including ibuprofen (Advil, Motrin) and opioids, have made acetaminophen the default pain reliever and fever reducer during those vital nine months.

Yet the Trump Administration highlighted a purported acetaminophen-autism link on Sept. 22, and there’s a pending U.S. Food and Drug Administration safety-label recommendation that pregnant women avoid acetaminophen unless “medically necessary,” as President Trump put it.

Dr. Jennifer Braverman, a maternal fetal medicine specialist who sees patients at UCHealth Maternal Fetal Medicine Clinic – Anschutz Medical Campus, is among the many medical experts who disagree with the administration’s position.

“The best-available data do not support this recommendation,” said Braverman, who is also an associate professor at the University of Colorado School of Medicine.

Many studies have explored acetaminophen and autism and found ‘no causative link’

Among those who share Braverman’s opinion that Tylenol use during pregnancy does not cause autism are the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the national medication-safety authorities of the European Union, the United Kingdom, and Australia.

Supporting their view is recent peer-reviewed research, such as a study involving 2.5 million Swedish children published in the Journal of the American Medical Association in August and a Japanese study of 217,000 children published earlier this month. Both found no relationship between maternal acetaminophen use and autism.

But other studies have noted an association — though never a causative link — between taking acetaminophen during pregnancy and autism. A recent review by a Harvard-led team taking eight studies into account concluded that a child exposed to acetaminophen in utero had a higher risk of developing autism than one not exposed to it.

What causes autism? There are many causes, including genetics, older parents and pollution. 

No one knows exactly what causes autism, and improvements in diagnosing it probably only play a partial role in the rising number of children identified with the neurodevelopmental disorder. We do know that there are both genetic and environmental factors involved. Boys are about three times more likely to have autism than girls, and younger siblings of a child with autism have six times the likelihood of having autism, suggesting a genetic cause. Also, older parents are more likely to have a child with autism.

Proven environmental factors range from air pollution to low birth weight to mom’s health, in particular with respect to gestational diabetes, maternal obesity, and infection during pregnancy. (Vaccines, to reiterate, do not cause autism.)

Such a range of potential causes, and the likelihood that combinations of factors trigger each autism case, cast doubt on acetaminophen’s possible role in rising autism rates. Many of the early studies that suggested a potential link between acetaminophen use and autism did not account for the reason the pregnant person was taking Tylenol in the first place, Braverman says.

“It is possible that fever, inflammation, or infection, rather than acetaminophen use itself, led to the association seen in these small studies between acetaminophen exposure and autism,” she said.

Untreated fevers are dangerous for pregnant women and babies

While maternal pain can bring problems such as depression and high blood pressure, Braverman is particularly concerned that women may choose to let a fever burn rather than take acetaminophen to douse it. In the first trimester, she says, fever is associated with increased risk of birth defects such as cleft lip and palate, as well as serious neural-tube defects such as spina bifida and anencephaly. In late pregnancy, fevers can boost the risk of miscarriage, stillbirth, and preterm birth, she says.

“Fever has been associated with a lot of problems for babies,” Braverman said. “And what I worry about in particular is that people are either going to not treat fever, which we know is dangerous for fetuses, or that people are going to turn toward medications that we know are unsafe in pregnancy, things like ibuprofen or opioids.”

Regarding acetaminophen, Braverman says, “I think it’s the safest option we have.”

Acetaminophen is safe in general

Dr. James Burton, a transplant hepatologist, agrees. Burton specializes in the care of patients with acute and chronic liver disease at the UCHealth Hepatology Clinic — Anschutz Medical Campus. He says it takes one-time doses 10 to 15 times greater than the typical high-end dose of one gram — or six times the typical dose over several days – for acetaminophen to cause acute liver damage.

“Tylenol is safe to take, even if you have cirrhosis, and we recommend Tylenol or acetaminophen to our patients on our transplant list,” said Burton, who is also a professor at the University of Colorado School of Medicine.

“It’s actually safer than taking ibuprofen in people with chronic liver disease, because ibuprofen can cause kidney dysfunction and it can cause gastrointestinal bleeding,” Burton said.

While Braverman may view the focus on prenatal acetaminophen and autism to be misplaced, she agrees that pregnant patients should only take the medications they need to stay healthy.

“I tell my patients, whether you’re pregnant or not, you shouldn’t take a medicine for no reason,” she said. “If you have a fever, if you have pain, we know that Tylenol is a safe and effective treatment for those things, and there aren’t a lot of other options that are safe or effective in pregnancy.”