The research brief is a short introduction to interesting academic work.
There is increasing evidence that the use of acetaminophen (known under its brand name Tylenol) during pregnancy may pose a risk to the development of the fetus and early childhood. This is the conclusion of a new review study by which I am the lead author.
Acetaminophen, whose chemical name is paracetamol, is an over-the-counter drug that doctors widely recommend for pain relief and fever.
Our research is based on the evaluation of 25 years of research in the fields of human epidemiology, animal and in vitro research and concluded that prenatal acetaminophen exposure may increase the risk of dysplasia of the reproductive organs. We found that the risk of neurodevelopmental disorders is increased, mainly attention deficit hyperactivity disorder and related behaviors, as well as autism spectrum disorders, as well as language delay and decreased IQ.
In a consensus statement (a broad agreement reached by our multidisciplinary international expert panel) published in September 2021 on Nature Reviews Endocrinology, 91 clinicians and researchers called for caution and additional research.
Why it matters
Acetaminophen is the active ingredient in more than 600 prescription and over-the-counter drugs. More than 50% of pregnant women in the world use it, and at least 65% of pregnant women in the United States use it. Studies have shown that acetaminophen is an endocrine disruptor that may interfere with healthy nerves and hormones necessary for reproductive development.
Current guidelines recommend acetaminophen as the first-choice analgesic during pregnancy, because other analgesics such as ibuprofen and aspirin are considered unsafe after the second trimester.
In the past 40 years, the incidence of reproductive disorders and neurodevelopmental disorders (such as ADHD and autism spectrum disorders) has been increasing.
During the same period, the use of acetaminophen increased during pregnancy. We concluded that because acetaminophen is so common during pregnancy, if its use leads to a small increase in individual risk, it may have a significant impact on these diseases in the entire population.
Don’t know what
It is unethical to conduct experiments that may harm human life. Therefore, in order to better understand the direct effects of acetaminophen during pregnancy, we must rely on human observations and experimental studies to assess the possibility of causality. But to really solve these problems, we need to conduct a human cohort study to accurately capture the time and reason of taking acetaminophen during pregnancy. In addition, we hope to see research that allows us to better understand biological pathways.
It is worth noting that acetaminophen is also the most commonly used medicine for infants. More research is needed to determine whether this approach is safe for the developing brain.
Acetaminophen is currently used almost ubiquitously during pregnancy, partly because it is widely believed to have limited side effects and negligible risks, even among doctors. But more and more studies have shown that the abuse of acetaminophen during pregnancy – especially for diseases such as chronic pain, low back pain and headaches – may be unfounded and unsafe.
In our consensus statement, we urge health professionals and pregnant women to be educated about the risks and benefits of acetaminophen during pregnancy.
Based on our extensive review of the evidence—and limited knowledge of the necessary treatments for high fever and severe pain—we advise pregnant women not to use acetaminophen unless medically recommended by the doctor. Women should also minimize the risk to the fetus by using the lowest effective dose in the shortest possible time.
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