Prenatal paracetamol use does not increase child neurodevelopmental risks

Researchers from the University of Hong Kong (HKUMed), along with Aston Pharmacy School's Professor Ian Chi-Kei Wong, have shown that using paracetamol (acetaminophen) during pregnancy does not increase a child's risk of developing autism spectrum disorder (ASD) or attention‑deficit hyperactivity disorder (ADHD).

Paracetamol is the most widely used medication for pain and fever during pregnancy. Yet, following statements from the US administration linking it with ASD, its safety became a subject of intense public and scientific debate. While the World Health Organization and other health bodies reaffirmed its safety profile, robust evidence was urgently needed, which this study provides.

To overcome the criticism that mothers taking paracetamol are different from those that do not, the study design compares siblings from the same mother, with at least one sibling exposed to paracetamol during pregnancy and the other unexposed. The research team analysed electronic medical records from 708,020 mother-child pairs in Hong Kong spanning over two decades, from 2000-2023.

Using a sibling-matched design that accounts for genetic and environmental factors, the study showed no association between prenatal paracetamol exposure and the risk of ASD or ADHD in offspring. Results remained consistent regardless of dosage, timing of exposure (i.e., first, second, or third trimester), or pattern of use (i.e., sporadic, intermittent, or persistent use).

The findings, published in JAMA Internal Medicine, provide timely reassurance for expectant mothers and clinicians in Hong Kong and globally.

I had herpes zoster during my pregnancy, yet I did not take paracetamol for myself at that time because of the concerns in the news. As a researcher and mother, I share the deep-seated concerns that many women face. Our study provides the reassurance I wish I had and would have helped me with the pain I was experiencing."

Dr Shan Luo, research assistant professor, Department of Family Medicine and Primary Care, HKUMed

Professor Wong, Regius Chair in Pharmacy at Aston University, and a professor in the Department of Pharmacology and Pharmacy, HKUMed, said:

"Monitoring the long-term outcomes of children with in-utero drug exposure requires an incredibly robust data infrastructure. Aston Pharmacy School and HKUMed Department of Pharmacology and Pharmacy formed a strategic alliance with other international partners to address medication safety issues; consequently, we were able to rapidly address this urgent drug safety question with the necessary precision and scale."