If you were pregnant, did you ever take a Tylenol?

If not, you have unreal levels of tolerance for discomfort but if you did, and you think your child is hyperactive, a new study may have some answers. Not 'why' answers, just a 'perhaps' answer. But look for mainstream media to declare that Tylenol causes attention-deficit/hyperactivity disorder (ADHD) in kids.

Acetaminophen is the most commonly used medication for pain and fever during pregnancy. But some studies have suggested that acetaminophen has effects on sex and other hormones, which can in turn affect neurodevelopment and cause behavioral dysfunction. The authors of a new paper in JAMA Pediatrics studied 64,322 children and mothers in the Danish National Birth Cohort (1996-2002). Parents reported behavioral problems on a questionnaire, and hyperkinetic disorders (HKDs, a severe form of ADHD) diagnoses and ADHD medication prescriptions were collected from Danish registries.

They found that more than half of the mothers reported using acetaminophen while pregnant. No surprise there. But then they also found that the use of acetaminophen during pregnancy appeared to be associated with a higher risk of HKD diagnosis, of using ADHD medications or of having ADHD-like behaviors at age 7 years. The risk increased when mothers used acetaminophen more than one trimester during pregnancy.

“Maternal acetaminophen use during pregnancy is associated with a higher risk for HKDs and ADHD-like behaviors in children. Because the exposure and outcomes are frequent, these results are of public health relevance but further investigations are needed,” they conclude.

In an accompanying editorial (JAMA Pediatr doi:10.1001/jamapediatrics.2013.5292), Miriam Cooper, M.R.C.Psych, M.Sc., of Cardiff University School of Medicine, and colleagues write, “Indeed, causation cannot be inferred from the present observed assocaitions, and Liew et al are right to point out that a replication of their study is needed.

“In summary, findings from this study should be interpreted cautiously and should not change practice. However, they underline the importance of not taking a drug’s safety during pregnancy for granted, and they provide a platform from which to conduct further related analyses exploring a potential relationship between acetaminophen use and altered neurodevelopment.”

Citation: JAMA Pediatr, February 24, 2014. doi:10.1001/jamapediatrics.2013.4914