Acetaminophen During Pregnancy May Be Associated with Abnormal Fetal Neurodevelopment

updated Jun 20, 2023

A new paper published by JAMA Pediatrics examined acetaminophen use during pregnancy.  From the paper:

In this study, we have demonstrated that children exposed prenatally to acetaminophen in the second and third trimesters are at increased risk of multiple behavioral difficulties, including hyperactivity and conduct problems.

The authors stated that further research will be required to understand the mechanisms involved (as well as to replicate the findings), but they did offer some thoughts:

One mechanism might involve the endocrine-disrupting properties of acetaminophen. The disruption of the maternal hormonal environment could affect fetal brain development.

It is also known that acetaminophen crosses the placenta, and animal studies have shown that the fetus is capable of producing the toxic metabolites of acetaminophen.

Another study published in International Journal of Epidemiology in June 2016 found:

“Prenatal acetaminophen exposure was associated with a greater number of autism spectrum symptoms in males and showed adverse effects on attention-related outcomes for both genders.”

Co-author of that paper, Dr. Jordi Júlvez, also provided thoughts on a possible mechanism involved.  He commented,

“Paracetamol could be harmful to neurodevelopment for several reasons. First of all, it relieves pain by acting on cannabinoid receptors in the brain. Since these receptors normally help determine how neurons mature and connect with one another, paracetamol could alter these important processes. It can also affect the development of the immune system, or be directly toxic to some fetuses that may not have the same capacity as an adult to metabolize this drug, or by creating oxidative stress.”

Some additional studies from 2013,  2014, and 2015 add to the body of evidence, but more research is still needed.


Update: 2018 Review: