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Last September, following a White House announcement suggesting a link between acetaminophen use during pregnancy and rising rates of autism, we looked at a statement from the World Health Organization and other medical stakeholders which pushed back on the theory.
We've looked at potential drivers of increased autism often over the years, and after genetics, environmental exposures - and increased recognition of those on the spectrum - fevers during pregnancy are frequently cited (see Molecular Psy.: Increased Autism Risk Linked To Prenatal Fever).While no drug can claim to be 100% safe in 100% of the people that take it, these OTC pain/fever relievers have long been considered the safest option for both the mother and unborn child.
While a few studies have claimed a statistical link between acetaminophen use during pregnancy and autism (Link), none have found a causal link, and a large 2024 study found `Acetaminophen use during pregnancy was not associated with children’s risk of autism, ADHD, or intellectual disability in sibling control analysis.'
The concern is: disparaging the only `presumed safe' option to reduce maternal fevers could actually end up increasing the incidence of autism, instead of decreasing it.
We revisited this story last January in The Lancet: Prenatal Paracetamol Exposure and Child Neurodevelopment: A Systematic Review and Meta-Analysis, which incorporated 43 studies (17 of which were combined in the meta-analysis), which reported:
Current evidence does not indicate a clinically important increase in the likelihood of autism spectrum disorder, ADHD, or intellectual disability in children of pregnant individuals who use paracetamol as directed, supporting existing recommendations on its safety.
Additional research is still needed to better understand heavy or prolonged usage, but these findings should be reassuring to anyone who chooses to use these drugs during pregnancy.
Under Implications of all the available evidence, the authors wrote:
Taken together with large-scale sibling-controlled studies from Sweden and Japan published in 2024 and 2025, our findings support the safety of paracetamol when used appropriately during pregnancy. They reinforce the guidance of major professional and regulatory bodies, including the American College of Obstetricians and Gynecologists, the Royal College of Obstetricians and Gynaecologists, and the European Medicines Agency, which continue to recommend paracetamol as the first-line analgesic and antipyretic in pregnancy.
Avoiding paracetamol based on inconclusive or biased evidence might increase the risk of maternal fever or untreated pain, both of which can harm pregnancy outcomes. Future research should focus on improving exposure measurement, standardising outcome definitions, and integrating mechanistic and family-based designs to clarify any residual uncertainties.
Admittedly, not a rock solid 100% guarantee of absolute safety; but in life, precious little is.
Weighing in on all of this, yesterday the CMAJ published a brief review on the use of acetaminophen in pregnancy, and they too find that `Current evidence does not indicate a causal link between acetaminophen use in pregnancy and adverse infant outcomes.'
For those looking for a bit more reassurance, I've posted their report below.
Acetaminophen in pregnancy
Jonathan S. Zipursky Rachela Smith and Tali Bogler CMAJ
June 01, 2026
DOI: https://doi.org/10.1503/cmaj.260138
Acetaminophen is the preferred analgesic and antipyretic agent for pregnant people
More than half of pregnant people use acetaminophen, most commonly for pain.1 Compared with alternatives, acetaminophen is the best studied analgesic and antipyretic in pregnancy and has the most reassuring maternal and fetal safety profiles. Major regulatory and obstetrical organizations support judicious use of acetaminophen as the first-line treatment for fever and pain in pregnancy.2
Studies on the risks of neurodevelopmental disorders related to acetaminophen use in pregnancy have not established causation
Some systematic reviews suggest small associations between prenatal acetaminophen use and autism spectrum disorder and attention-deficit/hyperactivity disorder. However, studies that rigorously control for potential confounders or emphasize sibling-controlled designs have typically found weaker or null associations.3,4 This suggests that unmeasured confounders (e.g., genetic and environmental factors) largely explain the associations with neurodevelopmental disorders.5 Randomized controlled trials have not been conducted, and therefore methodological weaknesses in existing observational studies limit conclusions about causation.
Data on fetal reproductive and endocrine effects show small, inconsistent associations
Results from observational studies linking prenatal acetaminophen use to abnormalities in the male reproductive tract are inconsistent; some studies have demonstrated small associations with cryptorchidism and reduced anogenital distance, while others have not.5 Furthermore, most studies relied on maternal memory of acetaminophen use in pregnancy, raising the potential for recall bias that may increase observed effect sizes or lead to spurious associations.
Untreated maternal fever has been associated with adverse fetal outcomes
Separating the potential effects of acetaminophen from those of the underlying condition is challenging. Treatment of fever in pregnancy is clinically indicated; in some observational studies, maternal fever was linked to increased risks of neurodevelopmental disorders.6 First-trimester fevers have been linked to congenital abnormalities such as neural tube, heart, and oral cleft defects.7
Counselling on acetaminophen use in pregnancy should emphasize a critical approach to interpreting the data
Current evidence does not indicate a causal link between acetaminophen use in pregnancy and adverse infant outcomes. Clear counselling by clinicians about the limitations of existing observational data can reduce unnecessary anxiety or avoidance of appropriate fever and pain treatment in pregnancy.
