Article image

Acetaminophen use during pregnancy linked to language delays in children

Researchers from the University of Illinois Urbana-Champaign have identified a significant association between the use of acetaminophen during pregnancy and language delays in children. 

Acetaminophen, widely recognized as the safest over-the-counter pain reliever and fever reducer for pregnant women, is used by 50 to 65 percent of women in North America and Europe. However, this study challenges the idea of its harmlessness during pregnancy.

Acetaminophen and child development 

Megan Woodbury, who is now a postdoctoral researcher at Northeastern University, led the study with Professor Emerita Susan Schantz as part of the Illinois Kids Development Study (IKIDS). The goal of IKIDS is to explore how environmental exposures during pregnancy affect child development.

Compared to previous research, the team used a different approach. “The previous studies had only asked pregnant people at most once a trimester about their acetaminophen use,” said Woodbury. “But with IKIDS, we talked to our participants every four to six weeks during pregnancy and then within 24 hours of the kid’s birth, so we had six time points during pregnancy.”

Focus of the study 

The researchers focused on 298 children, who were monitored prenatally and then assessed at the ages of two and three. At these ages, children undergo a period known as “word explosion,” making it an ideal time to evaluate language development.

The team utilized the MacArthur-Bates Communicative Development Inventories for assessing 2-year-olds. This involved parents reporting on their child’s vocabulary, language complexity, and the average length of their longest utterances. At age three, parents compared their child’s language skills to their peers.

Key findings

Significantly, the research linked increased acetaminophen use, especially during the third trimester, to modest but meaningful delays in early language development. 

“We found that increased use of acetaminophen – especially during the third trimester – was associated with smaller vocabulary scores and shorter ‘mean length of utterance’ at two years,” said Woodbury.

“At age three, greater acetaminophen use during the third trimester was related to parents ranking their kids as lower than their peers on their language abilities,” said Schantz. “That outcome was seen primarily in male children.”

Critical new insight 

One of the study’s most striking findings is that each instance of acetaminophen use in the third trimester was linked to an almost two-word reduction in the vocabulary of 2-year-olds. 

“This suggests that if a pregnant person took acetaminophen 13 times – or once per week – during the third trimester of that pregnancy, their child might express 26 fewer words at age 2 than other children that age,” said Woodbury.

Shantz noted that fetal brain development occurs throughout pregnancy, but the second and third trimesters are especially critical times. 

“Hearing is developing in the second trimester, but language development is already starting in the third trimester before the baby is even born,” said Shantz.

“It’s thought that acetaminophen exerts its analgesic effect through the endocannabinoid system, which is also very important for fetal development,” said Woodbury.

Study implications 

While the findings are significant, the researchers caution against alarm and emphasize the need for further, larger studies. They advise that acetaminophen should not be avoided for managing serious pain and fever during pregnancy, as conditions like high fever can be harmful. 

“There aren’t other options for people to take when they really need them,” said Schantz. “But perhaps people should use more caution when turning to the drug to treat minor aches and pains.”

The study is published in the journal Pediatric Research

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.


Check us out on EarthSnap, a free app brought to you by Eric Ralls and

News coming your way
The biggest news about our planet delivered to you each day