Acetaminophen Use During Pregnancy and Autism Risk
Acetaminophen at recommended doses can be used during pregnancy when medically indicated for pain or fever, as it remains the safest first-line analgesic option available. 1 However, use only when needed, at the lowest effective dose, for the shortest duration possible. 2
Safety Profile and Current Guidelines
The Society for Maternal-Fetal Medicine (SMFM) supports acetaminophen use during pregnancy when medically indicated, as it is considered safe for treating pain and fever in pregnant women. 1
The FDA reviewed available studies in 2015 and concluded that the weight of evidence is inconclusive regarding a possible connection between acetaminophen use in pregnancy and ADHD or autism in children. 2
Acetaminophen remains the preferred analgesic during pregnancy because alternatives carry known serious risks: NSAIDs should be avoided in first and third trimesters, and other pain medications have established teratogenic effects. 1
Autism Risk: What the Evidence Shows
The Most Recent and Highest Quality Evidence
The 2024 Swedish nationwide cohort study of 2.48 million children provides the strongest evidence to date and found NO association between prenatal acetaminophen use and autism when accounting for familial confounding. 3
- This study used sibling control analysis (the gold standard for addressing genetic and familial confounding) and found:
Earlier Observational Studies Showing Associations
Prior observational studies suggested possible associations, but had critical methodological limitations:
A 2016 Danish study (64,322 children) found prenatal acetaminophen use associated with ASD accompanied by hyperkinetic symptoms (HR 1.51,95% CI 1.19-1.92), but not with other ASD cases (HR 1.06,95% CI 0.92-1.24). 4
Multiple meta-analyses from 2018-2022 reported weak associations between prenatal acetaminophen and ADHD/ASD, but acknowledged substantial heterogeneity (I² = 68-93%) and significant methodological flaws. 2
Why Earlier Studies Were Flawed
All earlier observational studies showing associations had critical limitations that likely explain the apparent associations: 2
- Self-reported medication use (recall bias) 2
- No information on dosage, duration, or timing of exposure 2
- Outcomes measured by parental questionnaires rather than clinical evaluation 2
- Failure to control for familial/genetic confounding (the key issue resolved by the 2024 sibling study) 3
- Confounding by indication (women taking acetaminophen may have underlying conditions like infections or fever that independently affect neurodevelopment) 2
Clinical Recommendations
Use acetaminophen during pregnancy only when medically needed, at the lowest effective dose, for the shortest duration. 2, 1
Practical Guidance:
For moderate to severe pain or fever, acetaminophen remains the first-line recommendation. 1
For mild pain, consider non-pharmacological approaches first before medication use. 1
Avoid prolonged or excessive use (>28 days cumulative exposure), as this was associated with stronger associations in older observational studies, even though causality remains unproven. 2, 4
Balance the risks: Untreated fever and pain during pregnancy carry their own risks to maternal and fetal health that may outweigh theoretical neurodevelopmental concerns. 2
Common Pitfalls to Avoid:
Do not withhold necessary acetaminophen treatment based on inconclusive observational data, especially when the most rigorous 2024 study found no association. 3
Do not recommend NSAIDs as alternatives in first or third trimesters, as these have established risks. 1
Counsel patients that while earlier studies raised concerns, the highest quality evidence using sibling controls found no causal relationship. 3
The Bottom Line on Autism Risk
Based on the most recent and methodologically rigorous evidence (2024 Swedish sibling study), there is no credible evidence that acetaminophen use during pregnancy causes autism or other neurodevelopmental disorders. 3 Earlier associations appear to be explained by familial confounding rather than direct drug effects. 3