Tylenol during pregnancy not tied to increased risk of autism in children

A Danish nationwide cohort study published in JAMA Pediatrics found no significant association between maternal acetaminophen prescription during pregnancy and autism in offspring, with adjusted hazard ratios near 1 in both population and sibling analyses.

Danish researchers published a nationwide study in JAMA Pediatrics reporting no significant association between maternal acetaminophen prescriptions during pregnancy and autism in children. The team linked individual-level national demographic and health registers for singletons born in Denmark from January 1997 to July 2022 and followed them until diagnosis, emigration, or at least one year of age. The study followed earlier inconsistent findings and public discussion about possible links to acetaminophen use during pregnancy. An earlier umbrella review in BMJ and other recent analyses are part of the background for this ongoing research. Key findings: - The cohort included more than 1.5 million children; 2.1% were recorded as exposed to acetaminophen in utero. Among exposed children, 1.8% were later diagnosed with autism, compared with 3.0% in the unexposed group. - Exposure was identified by maternal fulfillment of prescriptions in the National Prescription Register; a sibling analysis compared groups with discordant prenatal exposure. - After adjustment, the population analysis produced an adjusted hazard ratio of 1.03 (95% CI, 0.95–1.12) and the sibling analysis an adjusted hazard ratio of 1.09 (95% CI, 0.91–1.27), neither showing a statistically significant increase in autism risk. - Stratified analyses of dose-response, timing by trimester, and analyses restricted to pregnancies after 2013 found no significant associations. - Study limitations include possible misclassification of outcomes and lack of individual-level data on over-the-counter medication use. Summary: The study adds to accumulating evidence that maternal acetaminophen use during pregnancy was not associated with a clear increase in autism risk in this large Danish cohort. Undetermined at this time.