If you're pregnant and you have a headache or a fever, Tylenol (acetaminophen) has long been at the top of the already short list of over-the-counter medications generally regarded as safe for both mothers and fetuses.
However, according to a study published in September 2021 in the journal Nature Reviews Endocrinology, mounting research shows that "prenatal exposure to acetaminophen might alter fetal development, which could increase the risks of some neurodevelopmental, reproductive and urogenital disorders."
Signed by 91 scientists from across the U.S., the U.K., Canada, Australia, Brazil, Scotland and Europe, a consensus statement published in the same journal draws a hard line, recommending that "pregnant women should forgo acetaminophen use unless medically indicated."
I've taken Tylenol during both my pregnancies. Many of my mom friends have taken it during their pregnancies. I'm sure my own mother took it when she was pregnant with me.
Doctors and midwives often fall back on Tylenol when pregnant women come to them looking for pain relief. But now, that's no longer a failsafe protocol.
Potential risks to the fetus from Tylenol in pregnancy
Performing a review of the most recent literature, the researchers found that acetaminophen exposure during pregnancy may be associated with reproductive and neurobehavioral abnormalities in both boys and girls.
In boys, exposure may increase the risk of reproductive abnormalities, including a higher risk of undescended testicles, and a reduced distance between the anus and the base of the penis, (termed the anogenital distance). Both of these factors may indicate "altered masculinization" and the potential for other reproductive disorders later in life.
In girls, prenatal acetaminophen exposure is associated with early puberty.
In both sexes, studies suggest exposure might increase the risk of attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, language delay and decreased intelligence quotient (IQ).
Figure 1 from Paracetamol use during pregnancy — a call for precautionary action.
More research is needed to assess the timing, duration and dosage of acetaminophen usage, but numerous animal studies also back up these findings.
In rats, fetal exposure to acetaminophen has been shown to also cause reproductive disorders, reduced fertility later in life and changes in cognitive function and behavior.
Figure 2 from Paracetamol use during pregnancy — a call for precautionary action.
It's unclear at what dosage Tylenol is harmful, but the strongest negative effects were observed with long-term use of acetaminophen (more than 2 weeks). If you happen to take it once or twice during your pregnancy at the minimum dose, you're much less likely to see such drastic repercussions.
Tylenol use is widespread
Acetaminophen is one of the most commonly used medications around the world—and it's often used in the general population without even a second thought. It's included in hundreds of other medications, including cough syrups, flu medicines, allergy medicines and sleep aids. It's often presumed benign, even though it's one of the major contributors to liver disease in the U.S. each year, writes doctor and midwife Aviva Romm, MD on a blog post about the safety of Tylenol in pregnancy.
Approximately 65% of pregnant women in the U.S. are estimated to have used Tylenol, and globally, more than 50% of pregnant women are expected to have used it (where it's widely known as paracetamol). Those statistics are also probably underreported. "One study showed that when asked about pharmaceutical use, many pregnant women did not report [acetaminophen] unless specifically asked," note the researchers.
The authors of the study acknowledge that acetaminophen "is widely considered to be the safest option for relief of pain and fever in pregnancy." And in fact, it's often the only option touted by healthcare professionals for their pregnant patients.
The researchers cite acetaminophen as an endocrine disruptor, saying it is known to "readily cross the placenta and blood-brain barrier," making its way to the fetus—with potentially harmful effects.
Now, given the growing body of evidence, it's time for increased awareness. The consensus statement calls on regulatory agencies, obstetrics and gynecological associations and healthcare providers to review the most recent research and reconsider their recommendations.
But where does that leave pregnant women dealing with pain in the meantime?
Pregnant women need pain management solutions
Clinical trials on the pregnant population are notoriously lacking (not without reason—performing studies on pregnant women can be ethically fraught), and pain during pregnancy is especially understudied. However, we do know that severe pain during pregnancy, left untreated, could have dangerous consequences for the mother, including an increased risk of anxiety, depression and high blood pressure.
And if you happen to get a fever above 100.4º during pregnancy, reducing it is your best course of action, as prenatal fever is associated with an increased risk of neural tube defects and cardiovascular disorders in the fetus.
But other pain management options are limited—or nonexistent. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen come with an increased potential risk of miscarriage in the first half of pregnancy, as well as birth defects. Aspirin carries a risk of bleeding risks, and opioids come with serious risks of birth defects in the brain, spine or spinal cord.
More research—and more options—are needed.
Pregnant women should avoid acetaminophen
The study's authors outlined a specific course of action, recommending that women be advised pre-pregnancy or early in pregnancy with the following guidance:
- Pregnant women should forgo acetaminophen use unless medically indicated.
- Pregnant women should consult with their physician or pharmacist if they are uncertain whether use is indicated and before using on a long-term basis.
- Pregnant women should minimize risk by using the lowest effective acetaminophen dose for the shortest possible time.
This is a major departure from the previous guidance of acetaminophen as generally accepted as safe. But if you've used Tylenol in a previous pregnancy, don't lambast yourself with mom guilt—you did the best you could with the information you had at the time.
"The chances are, statistically speaking, still low that this will have any impact on your baby. And for fever and significant pain, it's still considered the safest prenatal option. But we can't just assume it's safe and it can have an impact, so the goal is to avoid it when you can and keep your duration of use as brief as possible," writes Dr. Romm on her blog.
What to take instead of Tylenol during pregnancy
If the idea of even taking one Tylenol pill gives you pause, know that there are a few alternative remedies safe for pregnancy that can be used for mild pain. For fever reduction, however, given the potentially dire consequences of high, prolonged fever itself during pregnancy, taking a Tylenol to reduce the fever is still probably your safest option—talk to your doctor to discuss details.
Headache reduction alternatives:
- Hydration: In some cases, a headache is the body's way of signaling that you're dehydrated. Try upping your water intake, or sipping some cold coconut water, which packs in electrolytes.
- Protein and fat: You could be missing key nutrients in your diet—try rounding out your meals and snacks with more protein and plant-based fats to balance blood sugar.
- Magnesium: Taking 400 to 800 mg/day of magnesium glycinate or citrate can help relieve tension headaches and improve the stress response.
- Massage: Neck and shoulder massage can help release tension and reduce the resulting headaches.
- Stress management: Deep-breathing techniques may help reduce stress-based headaches.
Be sure to get your midwife or doctor's tips on headache management, too, and to discuss the frequency and duration of the headaches you're experiencing. If a headache comes on suddenly and severely, or you experience any vision changes, call your care provider right away.
But ultimately, as the study's authors state, "A balance must be struck between potential harm to pregnant people and/or their fetuses from untreated pain and fever, and the increased risks of harm to the fetus from medications." When thinking about using Tylenol or any other medication during pregnancy, it's all about the risk-benefit analysis. But being more informed about the risks can make a significant difference when you're weighing the scales.
Bauer AZ, Swan SH, Kriebel D et al. Paracetamol use during pregnancy—a call for precautionary action. Nat Rev Endocrinol. 2021. doi:10.1038/s41574-021-00553-7
Caution needed: paracetamol use in pregnancy. Nat Rev Endocrinol. 2021. doi:10.1038/s41574-021-00567-1
F.D.A. Safety Announcement: Drug Safety Communications. FDA has reviewed possible risks of pain medicine use during pregnancy. January 9, 2015.