Stronger evidence weakens proposed link between pregnancy paracetamol use and autism or ADHD

An umbrella review of more than 3 million participants found that associations between prenatal acetaminophen use and autism or ADHD largely diminished when lower-quality studies were excluded.

A new umbrella review has found that the apparent connection between acetaminophen use in pregnancy and autism or attention deficit hyperactivity disorder weakens markedly when only the strongest evidence is considered. The analysis, published in Developmental Medicine & Child Neurology, suggests that the common pain reliever, also known as paracetamol and widely sold as Tylenol, is unlikely to be a meaningful cause of either condition.

The findings land in the middle of a debate that has intensified in recent years and become politically charged. In September 2025, the US Food and Drug Administration began changing acetaminophen’s label to note a possible association with neurological conditions, while the American College of Obstetricians and Gynaecologists said the evidence still does not support a causal link and reaffirmed acetaminophen as the preferred pain reliever and fever reducer in pregnancy. A study published in JAMA in 2024 likewise found no increased risk of autism, ADHD or intellectual disability in children whose mothers used acetaminophen during pregnancy.

The new review, led by Hoda Tayebi-Hillali of the University of Santiago de Compostela, pooled seven previous meta-analyses covering more than 3 million participants. When all of the reviews were combined, the authors found only small associations: the relative risk was 1.17 for autism and 1.29 for ADHD. But many of the included reviews were judged to be low quality, and once the weakest were removed the estimates changed little, while the single high-confidence review found no statistically significant link with autism and only a modest association with ADHD.

The researchers then went a step further and examined the underlying studies themselves, focusing on those with the lowest risk of bias. That cut the autism estimate to 1.05, based on two studies, and reduced the ADHD estimate to 1.17, based on three. Tayebi-Hillali told PsyPost that the results shifted substantially once weaker evidence was excluded, and noted that sibling-comparison studies, which help account for shared genetic and family factors, did not support the stronger associations reported in some earlier work.

That pattern matters because pregnant women often take acetaminophen for fever, pain or infection, and those underlying problems can themselves affect fetal development. The review also found that several earlier studies relied on self-reported drug use, which can be unreliable, and that the remaining evidence base is too small to settle questions about dose, timing or duration of use. The authors said the remaining associations, even if real, would translate into only a very small absolute risk increase because autism and ADHD are relatively uncommon at the population level.

For parents and clinicians, the practical message is one of caution without alarm. The American College of Obstetricians and Gynaecologists says acetaminophen remains appropriate in pregnancy when needed, at the lowest effective dose and for the shortest necessary time, and the new review reaches a broadly similar conclusion. Tayebi-Hillali stressed that the study does not prove either safety or harm, but argues that current headlines often overstate what observational research can show. Untreated fever and pain in pregnancy can also carry risks, which is why medical guidance continues to favour careful, case-by-case use rather than blanket avoidance.