Summary: In one of the most extensive studies, researchers analyzed medical records of almost 2.5 million children known to be living with neurodevelopmental disorders. About of them, about 6% had pregnancy-related acetaminophen exposure. Their initial data cast some doubt regarding the association between acetaminophen fetal exposure and neurodevelopmental disorders risk. However, secondly, data analysis that looked at their siblings found no such association.
Acetaminophen is common worldwide. It is among the most commonly used medications for mild to moderate pains, chronic pain, and fever. It is also among the safest drugs, and thus, it is available as an over-the-counter medication. This means that millions of people use this drug. Moreover, it is also present in many non-prescription cold and flu remedies like Theraflu, Excedrin, and Mucinex, to name a few. Despite its proven safety, some concerns remain.
In the last few decades, there has been an increase in the cases of autism, ADHD, and intellectual disabilities among children. These are neurodevelopmental disorders. It means that their risk increases due to exposure to specific substances during pregnancy or due to certain lifestyle choices. Hence, it is vital to understand if acetaminophen, one of the most widely used painkillers, increases the risk of these issues.
However, identifying factors that increase the risk of neurodevelopmental issues like autism and ADHD is challenging. These issues do not essentially cause severe disability. Moreover, diagnostic criteria for these issues are continually changing, which also influences how many or how commonly children are diagnosed with the condition. That is why their diagnosis in developing nations is much less common compared to developed nations with more stringent diagnostic criteria and greater awareness among the population.
Largest Study to Date Did Not Show Association Between Acetaminophen Exposure During Pregnancy and Autism, ADHD, and Intellectual Disabilities Risk
The study analyzed data of 2,480,797 children born in 1995 to 2019 in Sweden. Out of them, 185,909 children were exposed to acetaminophen during pregnancy. Such massive studies have become possible due to the availability of electronic records and the ability to analyze these records using computing.
Initially, the study found that acetaminophen did increase the risk of these issues. The risk of these issues in those not exposed vs. those exposed was 1.33% vs. 1.53% for autism, 2.46% vs 2.87% for ADHD, and 0.70% vs 0.82% for intellectual disability. As one can see, the difference between the two groups was extremely small. Hence, it was not possible to say confidently that even such a minute increase in the risk was due to acetaminophen or for other reasons.
Despite their study showing minor differences in the prevalence of neurodevelopmental issues in the not-exposed vs. exposed group, researchers decided to try to understand why even this minor difference has emerged. Hence, they compared the data of all children diagnosed with neurodevelopmental issues (autism, AHDH, and intellectual disabilities) with their siblings who were not exposed to acetaminophen during pregnancy. This analysis did not show any difference between the two groups. Hence, it confirmed that the minute increase in risk found earlier was not due to the medication but rather due to genetic differences between the groups or it was familial.
The Bottom Line
Acetaminophen has been in clinical use for more than half a century, and it is identified as one of the safest painkillers. It is used for acute and chronic pains. Over the years, billions of people have been exposed to the drug. Therefore, its safety is well-established. Nevertheless, some doubts remain regarding its role in neurodevelopmental issues in children.
However, this study, one of the largest studies to date, has put an end to the debate that this commonly used painkiller might be increasing the risk of neurodevelopmental issues. Even initial data did not show any considerable association between acetaminophen exposure during pregnancy and ADHD, autism, or intellectual disability risk in children. However, secondary data analysis could confirm that even the minute risk identified initially was due to familial confounding factors, including genetic differences between the groups.
References
Ahlqvist, V. H., Sjöqvist, H., Dalman, C., Karlsson, H., Stephansson, O., Johansson, S., Magnusson, C., Gardner, R. M., & Lee, B. K. (2024). Acetaminophen Use During Pregnancy and Children’s Risk of Autism, ADHD, and Intellectual Disability. JAMA, 331(14), 1205–1214. https://doi.org/10.1001/jama.2024.3172
