Is Tylenol use during pregnancy linked with kids’ behavioral problems?

Does Tylenol taken during pregnancy make it more likely that the child born later will have learning and behavior problems? I do not think so, but a research paper published online today in JAMA Pediatrics says just that.

In this very long-term study, a British researcher says: "study results suggest prenatal use of acetaminophen by mothers at 18 and 32 weeks of pregnancy was associated with increased risk of conduct problems and hyperactivity symptoms in children, and maternal acetaminophen use at 32 weeks of pregnancy also was associated with higher risk for emotional symptoms and total difficulties in children."

The paper had a good number of positive aspects that supported the results. For example, it followed the children past their seventh birthday and there were almost 65,000 Danish sets of parents and children involved. Lastly, the results were cross-correlated with the parents taking acetaminophen after the child was born, which showed no effects of course.

They checked the mothers for infections, mental illness and many other factors that might cause harm to the baby independent of acetaminophen, but may encourage anti-pain or anti-fever medication. But there were also negative aspects. There was a lack of information on dosage or duration of acetaminophen use by the parents.

They also came in with two premises: 1) there is no explanation for why attention problems in children are increasing and 2) acetaminophen is a "hormone-disruptor" that could change the baby's brain in some way during pregnancy.

I personally think the first premise is wrong.  Over 40 years of observation, I have not seen the behavior of children change, but I have seen the increase in tendency to call many school problems, especially in boys, attention deficit disorder. There's also been a huge rise in the prescribing of stimulants for anyone not doing well in school.  A good deal of what is called ADHD is actually a combination of dyslexia and poorly structured family environments.

The second premise I am not competent to comment on, but it is very vague and broad. Another large problem is that fever itself is a teratogen (a factor that causes birth defects), thus not treating fever may also be a problem. The researchers acknowledged this issue as well, "However, the risk of not treating fever or pain during pregnancy should be carefully weighed against any potential harm of acetaminophen to the offspring."

Scientific studies are considered proven if there is less than one chance in twenty that the results could have happened by chance alone.  The paper checked acetaminophen because it is by far the most commonly used medication in pregnancy. However, they did not check any other medication or dietary supplement.  The only other study showing this same effect was published two years ago and used the same Danish data.  I would be more likely to believe this study if shown with other groups.

In any case, I will believe this study when a second study shows the same outcome.

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