Paracetamol during pregnancy does not increase the risk of autism or ADHD, according to study

The use of paracetamol the active ingredient in Tylenol, during pregnancy has not been linked to an increased risk of autism, ADHD or intellectual disability in children, a new study shows.

A searchpublished on Tuesday (9) in the magazine JAMAanalyzed the medical and prenatal records of around 2.5 million children born in Sweden between 1995 and 2019.

Previously, a statistical model that compared children exposed to paracetamol during pregnancy with those not exposed found that there was a marginally higher risk of autism, ADHD and intellectual disability in the exposed group.

However, a new analysis that studied exposure and outcomes among siblings (with the same biological parents) found that there was no evidence of an increased risk of autism, ADHD or intellectual disability associated with paracetamol use during pregnancy, according to the study led by scientists at Sweden's Karolinska Institutet and Drexel University.

To the sibling analysis are powerful because share genetic and environmental factors which eliminates some of the variables that can distort results in clinical trials, according to the study.

“Paired sibling control studies better control for environmental factors that researchers are unaware of,” says Eric Brenner, an assistant professor of pediatrics at Duke University who was not involved in the research, in an email to CNN . “It is very likely that siblings in the control group grew up in the same home, had similar diets and were exposed to similar environments, which allows researchers to better control environmental factors.”

Brenner said the large number of participants and sibling analysis are strengths of the study.

“This is a very large, well-designed study that found no association between acetaminophen use and neurodevelopmental impairment, including autism and ADHD,” he said. “Although any medication should always be used with caution and in consultation with an obstetrician, it appears that paracetamol is safe.”

These new findings refute recent research articles and statements that suggest there is an increased risk of autism, ADHD, and intellectual disability associated with acetaminophen use during pregnancy.

Although the FDA (Food and Drug Administration) of the United States and the European Medicines Agency consider paracetamol as posing minimal risk during pregnancy , a 2021 statement from an international group of scientists and doctors called for precautionary measures and recommended that pregnant people “discontinue acetaminophen unless its use is clinically indicated.” A number of research articles have linked acetaminophen use during pregnancy to an increased risk of ADHD and other neurodevelopmental disorders.

The authors of the new study wrote that “this suggests that the associations observed in other models may have been attributed to confounding factors.”

Confusion occurs when an external factor influences both the exposure and the outcome and creates a false association between the two. For example, the study found that parents with neurodevelopmental disorders (which have a strong heredity) are also more likely to use painkillers, such as acetaminophen, during pregnancy.

This relationship may make it appear that children exposed to acetaminophen during pregnancy are more likely to develop neurodevelopmental disorders, when in reality, Your greatest risk is due to genetics explains the study.

The study found significant differences between biological parents with greater paracetamol use and those with less or no use. Acetaminophen exposure was more common among children born to parents of a lower socioeconomic class, with a higher BMI (body mass index) at the start of pregnancy, those who smoked during pregnancy, and those diagnosed with psychiatric or neurological development conditions.

“The results suggested that there was no single irrefutable confounder, but that sociodemographic and health characteristics of multiple biological parents explained at least part of the apparent association,” the researchers wrote.

Interestingly, the study also found that other painkillers such as aspirin, other NSAIDs and opioids, were not associated with an increased risk of neurodevelopmental disorders in analyzes between siblings; Each type of painkiller has previously been linked to birth defects. In this study, aspirin use, in particular, was associated with a lower risk of neurodevelopmental disorders; however, this is an initial finding and more research is needed to understand this result, says Brenner.

“At this time, aspirin use is not routinely recommended during pregnancy, and I urge pregnant mothers to discuss its use with their obstetricians,” he says.

Brenner explains that fever is common and occurs in more than 10% of pregnant people. Most of the time, there are no effects on fetal development, he said, but fever in the first trimester has a greater association with serious birth defects such as cleft palate and heart defects.

Acetaminophen is one of the most used and studied medications during pregnancy and is considered safe for sensibly reducing fever and pain, says Brenner.

The FDA recommends not using NSAIDs (nonsteroidal anti-inflammatory drugs), such as aspirin and ibuprofen, during the third trimester of pregnancy, as these medications can cause a blood vessel in the fetus to close prematurely.

Yalda Afshar, resident assistant professor of obstetrics and gynecology at the UCLA David Geffen School of Medicine who was not involved in the new research, said in an email to CNN which recommends that people consult a healthcare professional about using or stopping any prescription or over-the-counter medication during pregnancy.

“We hope this study brings peace of mind to pregnant women who need to take acetaminophen to improve their health in some way,” he says.