NIH Study: Use of Popular Painkillers During Pregnancy Not Linked to Neurodisorders in Children

When women experience pain or fever during pregnancy, many doctors recommend acetaminophen for relief. But concerns about a possible link between these drugs and neurodevelopmental disorders have lingered. A multi-year study sponsored by the National Institutes of Health has produced results that contribute to the scientific consensus that these drugs are not the cause of neurodevelopmental problems.

Acetaminophen is the active pharmaceutical ingredient in some prescription products and popular over-the-counter pain relievers, most notably Tylenol and Excedrin. Although nonsteroidal anti-inflammatory medications provide an alternative approach to pain relief, these medications are not recommended during pregnancy because they can cause low amniotic fluid levels, among other problems.

The NIH-sponsored acetaminophen study was a collaboration between Swedish and American researchers. They evaluated data from the Swedish birth and prescription drug data for children born between 1995 and 2019. Follow-up took place until December 31, 2021. Of the more than 2.4 million Swedish children whose data was assessed, 185,909 (7.49%) were exposed to paracetamol during pregnancy. The results showed a slight increase in the risk of developing autism, attention deficit/hyperactivity disorder (ADHD) or intellectual disability in those who were exposed to acetaminophen, compared to those who were not.

To answer questions about whether other factors might be at play, scientists also analyzed children matched with a sibling as a control group. By checking for siblings, scientists could compare subjects that share many variables, such as genetics, environmental exposure and socioeconomic factors.

“Control analyzes of siblings found no evidence that acetaminophen use during pregnancy is associated with autism or intellectual disability,” the study authors wrote.

The American College of Obstetricians and Gynecologists recommends acetaminophen (also known as acetaminophen) for pain relief during pregnancy. The organization’s position is that the drug is one of the few painkillers that can be used safely during pregnancy and that there is no clear evidence showing a direct link between acetaminophen and fetal development problems. Lawsuits have been filed claiming a link, but they have not proven their claims. Late last year, a federal judge ruled that plaintiffs in a consolidated mass tort of nearly 500 cases failed to present scientific evidence that prenatal exposure to acetaminophen can lead to autism or ADHD.

There are limitations to the NIH study. It is based on data from prescription acetaminophen and from pregnant individuals self-reporting during prenatal care, the NIH said. Therefore, the study may not capture the full use or dosage of paracetamol in all people. However, the size of the study group and the ability to control for many other confounding factors support the conclusion that acetaminophen is not directly linked to an increase in autism, ADHD or intellectual disability, the NIH said. To fully understand the genetic and non-genetic factors that increase these risks, more research is needed.

The study was funded by the National Institute of Neurological Disorders and Stroke, part of the NIH. The results were published earlier this month in the journal JAMA.

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