Acetaminophen, better known under the brand name Tylenol, is an over-the-counter pain- and fever-reducing medication that is generally considered safe to use, even during pregnancy. In recent years, however, a slew of studies have cast some doubt on its safety during pregnancy. Some have claimed use of acetaminophen during pregnancy is linked to autism, ADHD (attention deficit/hyperactivity disorder) and behavioral issues in children.
While this may raise alarm bells for parents, it is important to understand how these studies were conducted in coming to their conclusions. In many cases, a closer examination of the data reveals that the risks have been overstated.
There have been 6 studies on this topic dating back to 2013 — the most recent came out just last month. All of these studies have reached similar conclusions, linking acetaminophen use during pregnancy to various behavioral issues in children.
FDA: No Clear Evidence Linking Tylenol to Developmental Issues
However, after conducting a review in January 2015 of studies to date, the FDA concluded that the results of the studies were too limited to make any definitive recommendations. Hal C. Lawrence, MD, executive vice president and CEO of the American College of Obstetricians and Gynecologists (ACOG), agrees.
The JAMA Pediatrics study in August “and other studies that have been conducted in the past, show no clear evidence that proves a direct relationship between the prudent use of acetaminophen during any trimester and developmental issues in children,” he tells MedShadow.
Let’s take a closer look at that JAMA Pediatrics study, which created scary headlines with the conclusion that behavioral problems were 20% to 45% more common in children whose moms took acetaminophen during pregnancy. The women were asked while pregnant about their acetaminophen use, but interestingly, were never asked how much they took or why. Also, the women who took Tylenol were more likely to have smoked or drank during the pregnancy, and more likely to have underlying psychiatric issues -– all factors that could influence behavior in their offspring.
the difference in the relative risk between women who did and did not take acetaminophen is extremely small.
As NPR pointed out, when these observations were factored in, the increase in behavioral problems in those whose mothers took acetaminophen greatly diminished, and even disappeared in some subgroups, compared to women who never took Tylenol.
Overall, the study found that a little less than 5% of the children examined in the study had behavioral problems. But only 2 percentage points separated those whose mothers had taken acetaminophen compared to those who hadn’t. In other words, the difference in the relative risk between women who did and did not take acetaminophen is extremely small.
Limitations in the Studies
Another limitation of many of these studies is that although they were based on interviews, many times, they were asked about acetaminophen use after their pregnancy. Studies that ask people to recall drugs they took a long time in the past are often inaccurate due to faulty memory.
The PLoS One study is perhaps the most significant evidence to date as it evaluates several medications — aspirin, antacids, NSAIDs (non-steroidal anti-inflammatory drugs), antibiotics and acetaminophen — whereas a majority of studies have only assessed the one medication. But again, this study showed a correlation, not a causation, between acetaminophen use and behavioral problems in children, and there could be other confounding factors involved.
All of these studies have “several limitations as it is not clear what dose of acetaminophen the mothers took, how long they took it, and for what reason. This is all critical information that is missing in order to begin to ascertain a cause and effect,” says Lawrence.
Therefore, “patients should not be frightened away from the many benefits of acetaminophen. The ACOG and obstetricians and gynecologists across the country have always identified acetaminophen as one of the only safe pain relievers for women during pregnancy,” he adds.
Behavioral disorders are a concern for parents as they affect 10-15% of children globally, with ADHD the most widely studied disorder. However, it is important to recognize that “behavioral disorders are multifactorial and very difficult to associate with a singular cause,” says Lawrence. “The brain does not stop developing until at least 15 months of age, which leaves room for children to be exposed to a number of factors that could potentially lead to behavioral issues.”
One important point to recognize in this discussion is that because acetaminophen is considered so safe, it is one of the most popular medications that pregnant women take. Between 40% and 65% of women in the studies said they used it during pregnancy. This compares to other commonly used medications during pregnancy, such as antibiotics (23.5%), antacids (17.4%), aspirin (5.3%) and NSAIDs (1.3%).
“The takeaways here are that physicians should not change clinical practice until definitive prospective research is done,” Lawrence notes. “And, as always, any medication taken during pregnancy should be used only as needed, in moderation, and after the expectant mother has consulted with her doctor.”