Acetaminophen in Pregnancy: Association With Autism and ADHD Risk Disappears in Sibling Comparison

Some studies have suggested that using the fever and pain reliever acetaminophen (paracetamol) during pregnancy could raise a child's risk of neurodevelopmental disorders. If true, this would greatly affect how pain and fever are managed in pregnant women. Researchers at the Karolinska Institutet in Sweden tested the question with nationwide data and a sibling comparison analysis and published the results in JAMA.

2.48 Million Children, Compared Among Siblings

The researchers followed 2,480,797 children born in Sweden over 25 years. Of these, 185,909 (7.49%) were exposed to acetaminophen in the womb; exposure was determined from information recorded in advance in prenatal care and prescription records. Outcomes were confirmed through diagnoses of autism spectrum disorder, attention-deficit/hyperactivity disorder (ADHD) and intellectual disability in health registries.

In the general analysis, risk in the exposed group was slightly higher, with hazard ratios of 1.05 for autism, 1.07 for ADHD and 1.05 for intellectual disability. However, when full siblings who share genes and family environment were compared, the hazard ratios were 0.98, 0.98 and 1.01, respectively, and the association disappeared, and there was no trend of rising risk with higher doses. The researchers suggested that the earlier association may have been due to familial confounding.

Limits

This is an observational study, and medicine bought over the counter may have been missing from the records. Because the data are from Sweden, care is needed in applying the findings directly to other countries, and medicine use during pregnancy should be discussed with a health care provider.