Should pregnant women use Tylenol? It's complicated

By: Emily Lind, Queen's University

Recently, European scientists published a study on the effect of acetaminophen on pregnant women. In a study of 70,000, they found a 19% increase in Autism Spectrum Conditions and a 21% increase in attention deficit hyperactivity disorder (ADHD) in children whose mothers reported taking the drug. This news becomes more concerning when you realize that acetaminophen (marketed as Tylenol) is used by ~56% of pregnant women in developed . Should we add acetaminophen to the list of items to avoid for pregnant women, alongside alcohol, smoking, and deli meat?

Maybe, but it is hard to say for sure. This study was a metadata analysis that pooled the findings from several separate studies. Each separate group of mothers and children was assessed using different instruments. This could mean that there is varying sensitivity between test groups, with some groups potentially over reporting ASC and ADHD. The researchers also couldn’t analyze the data based on the amount of acetaminophen taken by expectant mothers, which is a very important variable. There is a big difference between taking a Tylenol once in nine months and popping a pill every day for the entire gestation.

In studies on rats, acetaminophen has been found to disrupt brain development. But does that mean that human brains are also susceptible to damage by the drug? Multiple studies have found that acetaminophen can cross the human placental barrier, meaning that when the mother takes it, the baby also receives some of the drug. Acetaminophen can remain in the infant’s blood for a long time.

In an earlier publication, Yeulong et al. studied the correlation between ADHD, ADD and acetaminophen exposure using umbilical cord blood samples. They found a significant link between acetaminophen metabolites and ADHD diagnosis. Yeulong et al. suggested that the reason developing humans can’t handle acetaminophen is that fetuses have limited liver metabolism capacity, meaning toxic acetaminophen metabolites remain in babies for much longer than adults.

However, expectant mothers shouldn’t panic over acetaminophen use. Yuelong et al. also state that the correlation between acetaminophen and ADHD was dose dependent. This means that there is a big difference between taking the occasional acetaminophen and taking it every day. The European researchers concluded that while women shouldn’t be barred from acetaminophen consumption, they should also avoid it unless necessary. Current recommendations in Canada are that occasional acetaminophen use during pregnancy is okay, but that long-term use needs doctor supervision. The problem is that acetaminophen is considered the safest pain killer for pregnant women, so no alternatives really exist. Expectant mothers are again burdened with conflicting advice in terms of balancing self care and the health of their child.

Edited by B.G. Borowiec and A.E. McDonald. Header photo from Wikimedia Commons.