Study reveals no causal link between neurodevelopmental disorders and acetaminophen exposure before birth

NIH-funded research in siblings finds previously reported connection is likely due to other underlying factors.

What

Acetaminophen exposure during pregnancy is not linked to the risk of developing autism, ADHD, or intellectual disability, according to a new study of data from more than 2 million children in Sweden. The collaborative research effort by Swedish and American investigators, which appears in JAMA, is the largest of its kind and was funded by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH).

Scientists compared siblings — who share genetics and other variables such as parental health, environmental exposures, and socioeconomic factors — and were able to limit the influence of other potential risk factors. This allowed them to focus specifically on, and eliminate, the risk associated with acetaminophen. The study design was unique due to the size of the population captured in the Swedish Medical Birth Register and the Swedish Prescribed Drug Register. Before siblings were considered, there appeared to be a small increase in risk for neurodevelopmental disorders in children exposed to acetaminophen, which was noted in previous studies.

Acetaminophen is commonly used as a pain reliever and fever reducer and is found in a variety of medicines available over the counter and via prescription. It is often taken during pregnancy instead of nonsteroidal anti-inflammatory drugs, known as NSAIDs, which can cause low levels of amniotic fluid, according to the Food and Drug Administration. The reasons pregnant people might take acetaminophen, including fever, or conditions such as chronic migraine, could be, and in some cases are, associated with an increased risk for later neurodevelopmental disorders following pregnancy. 

One limitation of this study is that it relies on data from prescribed acetaminophen and from self-reporting from pregnant people during prenatal care. It may not capture all use or dosage in all people, particularly over-the-counter medicines. However, the number of patients included in the study sample and the ability to control for many other confounding factors support the conclusion that acetaminophen is not directly linked to an increase link of autism, ADHD, or intellectual disability.  

To inform best preventative strategies, additional research is required to fully understand the genetic and non-genetic factors that increase the risk of autism, ADHD, and intellectual disability.

This study was supported by NINDS (NS107607).

Who

Vicky Whittemore, Ph.D., program director, NINDS

Article

Ahlqvist VH, et al. “Acetaminophen use during pregnancy and children’s risk of autism, ADHD, and intellectual disability.” JAMA. April 9, 2024. DOI: 10.1001/jama.2024.3172

NINDS is the nation’s leading funder of research on the brain and nervous system. The mission of NINDS is to seek fundamental knowledge about the brain and nervous system and to use that knowledge to reduce the burden of neurological disease.

About the National Institutes of Health (NIH):
NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

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