An interesting study in this week’s JAMA Pediatrics is sure to spark lots of conversation but I will start with the Editor's summary which reminds us this is an interesting observation but too early to say there is a direct causal link. So what is the controversy all about?

In this study children of women who used the pain reliever acetaminophen during pregnancy appear to be at higher risk for attention-deficit/hyperactivity disorder (ADHD)-like behavioral problems and hyperkinetic disorders- HKDs, a severe form of ADHD)

As the authors point out in their summary, acetaminophen is the most commonly used medication for pain and fever during pregnancy. Some recent studies have suggested that acetaminophen has effects on sex hormones as well as other hormones, which can in turn affect neuro development and cause behavioral dysfunction.

The authors studied 64,322 children and mothers in the Danish National Birth Cohort (1996-2002). Parents reported behavioral problems on a questionnaire, and HKD diagnoses and ADHD medication prescriptions were collected from Danish registries.

What was found was that more than half of the mothers reported using acetaminophen while pregnant. 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 in more than one trimester during pregnancy.

The researchers concluded that '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.' And that statement is key in understanding and interpreting the results of this study.
In an editorial it was noted that this is an interesting new study. But causation cannot be stated from the present observed associations.

While findings from this study should be looked at and spark further research, it should not change practice. However, they underline the importance of not taking a drug’s safety during pregnancy for granted.