Is acetaminophen safe for pregnancy? Maybe not!

It’s an unfortunate fact of pregnancy that moms-to-be are guaranteed a plethora of pain and discomfort during their pregnancies. There will be headaches, fever, inflammation, muscle aches, and other varieties of pain, all ranging from mild to severe pain. It’s not surprising that many pregnant women frequently take over-the-counter medications, such as ibuprofen and acetaminophen (known as paracetamol in Europe), on a fairly regular basis during gestation.

Can pregnant women take ibuprofen (Advil)?

I get asked a lot “is Advil safe during pregnancy” and I tell my patients “it is not recommended.” Last October, the US Food and Drug Administration (FDA) issued a drug safety communication warning that beginning a couple of weeks before the third trimester, the use of nonsteroidal anti-inflammatory drugs (NSAIDs) might cause rare but serious kidney defects in unborn babies.

NSAIDs include ibuprofen, aspirin, naproxen, and a host of other medications. Meanwhile, acetaminophen is the active ingredient in Tylenol, as well as several other over-the-counter pain relievers.The number of mothers willing to take even the remotest possible risk that their babies will develop a potentially fatal disorder is zero. So, the use of NSAIDs for pain relief and mild fever during pregnancy was immediately and permanently ruled out.

Can pregnant women take Tylenol (acetaminophen)?

Maybe. Pregnant people were therefore grateful that acetaminophen, the other primary source of over-the-counter relief for moderate fever and pain, was considered relatively harmless during pregnancy with minimum side effects. In fact, the Centers for Disease Control (CDC) currently offers the opinion that “acetaminophen appears to be the best option for treatment of fever during pregnancy.”

Is acetaminophen safe for pregnancy?

The CDC’s reassuring message might need to change when they (or the FDA) get around to reviewing a recently issued consensus statement concerning the adverse effects of acetaminophen. The statement was written by 13 leading medical researchers and signed by another 78 internationally renowned specialists working in disciplines such as epidemiology, neurological studies, obstetrics, gynecology, and pediatrics.

Tylenol safety during pregnancy is reviewed

The statement, published in Nature Reviews Endocrinology, reviews and summarizes the last few decades of research concerning the safety of acetaminophen. The statement notes that, even before the FDA’s warning about the hazards of ibuprofen and other NSAIDs, acetaminophen was the most popular over-the-counter medication among pregnant people

Almost 70% of pregnant people in the United States and nearly 60% in western and northern Europe report using acetaminophen during their pregnancies.

There have been literally dozens of research papers published in the last 25 years about the safety, or lack thereof, of using acetaminophen during pregnancy.

Two of the statement’s co-authors, Ann Z. Bauer and Shanna Swan, observed in a recent interview that prenatal exposure to acetaminophen during pregnancy may result in significantly increased risk of:

• Attention Deficit Hyperactivity Disorder (ADHD)
• Autism Spectrum Disorder (ASD)
• Neurodevelopmental conditions
• Language delays
• Asthma
• Birth defects
• Behavioral problems

Beginning in the 1990s, scientists have increasingly examined the relationship between acetaminophen and fetal development problems. The resulting reports, published in both the United States and Europe, have shown that there is a very strong link between the two.

But the FDA and the CDC have been reluctant to change the position they share, that acetaminophen is the best option left after the near banning of NSAIDs. That hesitancy has been based on flaws in the research methodology, flaws that the researchers themselves admit do exist.

Why are we just learning this now?

There were major shortcomings in earlier research including the fact that all but two of the earlier studies relied entirely on data from questionnaires filled out, after the fact, by the participating mothers. The recollection of those women is no doubt far less than perfect, and their credibility is not assured.

The second major flaw in the studies’ protocols is the lack of any way to ascertain the dosage taken, the frequency that the dosage was taken, and for how long the medication was used during each pregnancy.

A new 2020 study analyzed a baby’s first poop for prenatal acetaminophen

The study, designed and executed at the Centre Hospitalier Universitaire de Sherbrooke, in Québec, Canada, eliminated the last major flaw in the acetaminophen studies’ methodologies.

Instead of sampling blood from an umbilical cord, the Sherbrooke researchers analyzed the babies’ meconium – that’s a euphemistic word for a baby’s first poop. The first poop after birth has been accumulating within the fetus ever since its intestines started functioning. Analysis of the meconium gives researchers invaluable data regarding both the dosage and the duration of the mother’s acetaminophen ingestion.

The Johns Hopkins and Sherbrooke studies overcame the last major defects in the prior research. The Johns Hopkins study (which was limited to ADHD and autism) first divided the children into three groups based on the levels of acetaminophen in their cord blood.

• The results showed that the children whose cord blood samples contained the highest levels of acetaminophen were 2.86 times more likely to be diagnosed with ADHD than were the children with the lowest levels of acetaminophen in their cord blood.
• The children with the highest levels of acetaminophen were 3.62 times as likely to be diagnosed as being on the autism spectrum than were the children with the lowest level of acetaminophen. (All 996 child participants in the Johns Hopkins study had at least some level of acetaminophen in their system at birth.)

The Sherbrooke study, which was limited to ADHD alone, focused on 345 children from whom meconium samples were collected and who were tested for ADHD when they were 6 to 7 years old.

• The use of acetaminophen was detected in the meconium of 199 children (57%)
• ADHD was diagnosed in 33 children (9.6%)

A finding of acetaminophen meant that the child was 2.43 times more likely to be diagnosed with ADHD than a child whose system contained no acetaminophen.

Researchers and clinicians now agree on how to use acetaminophen during pregnancy

There are times when the benefits of acetaminophen will clearly outweigh any attendant risk. As an example of those times, a pregnant person’s high fever is never good. Depending on when an elevated body temperature occurs during pregnancy, prolonged fever can lead to congenital abnormalities in the fetus, particularly the very serious conditions of neural tube defects or spina bifida.

So until the FDA changes its position by offering updated guidelines, pregnant women are advised to use acetaminophen for the shortest possible time. The only way to determine what acetaminophen use is best for you is through prolonged, thorough, and candid discussions with your attending healthcare provider.

The American College of Obstetricians and Gynecologists (ACOG) issued a statement in response to the consensus statement. It emphasized that neurodevelopmental disorders are complicated and multifactorial and the studies don’t show evidence of a direct relationship between acetaminophen and fetal developmental issues. Short-term use of acetaminophen is still the best option during pregnancy and ACOG warns “patients should not be frightened away from the many benefits of acetaminophen.”

About Dr. Aliabadi

As one of the nation’s leading OB/GYN’s, Dr. Thaïs Aliabadi offers the very best in obstetrics and gynecology, including telehealth appointments. Together with her warm professional team, Dr. Aliabadi supports women through all phases of life. She creates a special one-on-one relationship between patient and doctor.

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