Use of acetaminophen (paracetamol) during pregnancy and the risk of attention-deficit/hyperactivity disorder in the offspring.

Prenatal exposure to acetaminophen may result in compromised neurodevelopment through inflammatory and immunologic mechanisms, through predisposition to oxidative stress, and through endocrine, endogenous cannabinoid, and other mechanisms. Several small and large prospective studies have found an association between gestational acetaminophen exposure and attention-deficit/hyperactivity disorder (ADHD)-like behaviors, use of ADHD medication, and ADHD diagnoses in offspring during childhood; the only negative study was a small investigation that examined only one aspect of attention as an outcome. Creditably, most of the studies adjusted analyses for many (but not all) confounds associated with ADHD risk. Importantly, one pivotal study also adjusted for pain, infection, inflammation, and fever to reduce confounding by indication; this study found a dose-dependent risk. In the light of the finding of a single study that infection and fever during pregnancy by themselves do not raise the ADHD risk, it appears possible that the use of acetaminophen during pregnancy is itself responsible for the increased risk of ADHD. This suggests that acetaminophen may not be as safe in pregnancy as is widely believed. However, since fever during pregnancy may itself be associated with adverse gestational outcomes, given the present level of uncertainty about the ADHD risk with acetaminophen, it is suggested that, until more data are available, the use of acetaminophen in pregnancy should not be denied in situations in which the need for the drug is clear.