Researchers found that previous reviews often relied on weak or biased data, and most did not properly account for genetic or environmental factors shared by families. When these factors were considered, any apparent link between acetaminophen use and neurodevelopmental disorders largely disappeared.
An extensive review of existing studies, published in The BMJ on November 10, finds no clear evidence that using acetaminophen (Tylenol) during pregnancy increases the risk of autism or ADHD in children. The new analysis was conducted in response to growing public debate about the safety of acetaminophen use while pregnant.
The study authors emphasize that regulators, healthcare providers, pregnant women, parents, and those affected by autism and ADHD should be aware of the poor quality of prior evidence. They recommend that acetaminophen continue to be used when needed to relieve pain or reduce fever during pregnancy, consistent with current medical advice.
Acetaminophen (called paracetamol outside the USA and Japan) remains the standard and recommended treatment for pain and fever in pregnancy and is considered safe by regulatory agencies around the world.
Reviewing Data From 40 Studies
The team identified nine systematic reviews that together covered 40 observational studies on acetaminophen exposure during pregnancy and later neurodevelopmental outcomes in children. Four of these reviews included meta-analyses (a statistical technique that combines data from multiple studies to produce a more precise estimate of effect).
Each review was carefully assessed for bias using recognized evaluation tools, and the researchers rated their confidence in the findings as high, moderate, low, or critically low. The amount of overlap between studies in the reviews was also recorded and found to be very high.
Although all reviews reported a possible to strong link between maternal acetaminophen use and autism or ADHD, seven of the nine reviews urged caution when interpreting those findings. Most warned that the results could be skewed by unmeasured factors, known as confounders, such as family genetics or parental health differences.
Overall, confidence in the findings was rated as low for two reviews and critically low for seven. Only one review included two studies that adequately controlled for shared genetic and environmental influences between siblings and accounted for other important factors, including parental mental health, background, and lifestyle.
Sources:
https://unsplash.com/s/photos/tylenol
https://www.sciencedaily.com/releases/2025/11/251110021050.htm
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