Several studies have found a statistical association between acetaminophen use during pregnancy and autism in children, but the strongest evidence to date suggests this link is not causal. A 2025 meta-analysis published in The Lancet, drawing on a Swedish cohort of 2.48 million births, found no increased likelihood of autism when researchers compared siblings within the same family. The FDA has nonetheless initiated a label change to flag the possibility, while medical organizations maintain that acetaminophen remains the safest pain and fever reliever available during pregnancy.
What the Research Actually Shows
Dozens of observational studies over the past decade have reported that children whose mothers used acetaminophen during pregnancy are somewhat more likely to be diagnosed with autism or ADHD. These findings generated significant media attention and fueled lawsuits against manufacturers. But observational studies can only show that two things occur together. They cannot prove one causes the other.
The most powerful way to untangle this is a sibling comparison: if acetaminophen truly increases autism risk, a child whose mother took it during that specific pregnancy should be more likely to develop autism than a sibling whose mother did not. When researchers applied this method to 2.48 million Swedish births, the association disappeared. The hazard ratio was 0.98, meaning exposed and unexposed siblings had essentially identical rates of autism. That result strongly suggests something else shared within families, rather than the drug itself, explains the pattern seen in earlier studies.
Why Earlier Studies May Have Been Misleading
The most likely explanation is confounding: the reason a pregnant woman reaches for acetaminophen matters as much as the drug itself. Fever and infection during pregnancy have been linked to a roughly 16 to 32 percent increased risk of autism in some analyses. If women who experience more infections also take more acetaminophen, the drug looks guilty by association.
Even the infection link appears to be largely a mirage. A large Swedish study found that maternal infection in the year before pregnancy (when it could not possibly affect the fetus) predicted autism just as strongly as infection during pregnancy. And when siblings were compared, the infection-autism association dropped to near zero. This pattern points to shared genetic or environmental factors within families, not to any specific exposure during pregnancy, as the real driver.
The FDA Label Change
In September 2025, the FDA announced it would begin the process of updating acetaminophen labels to mention the possible association with neurodevelopmental conditions. FDA Commissioner Marty Makary framed the move as informational, not as a directive to stop using the drug: “The precautionary principle may lead many to avoid using acetaminophen during pregnancy, especially since most low-grade fevers don’t require treatment. It remains reasonable, however, for pregnant women to use acetaminophen in certain scenarios.”
The agency was careful to note that a causal relationship has not been established and that contrary evidence exists in the scientific literature. It also pointed out that acetaminophen is the only over-the-counter drug approved for treating fever during pregnancy, and that both aspirin and ibuprofen carry well-documented risks to fetal development.
What Medical Organizations Recommend
The American College of Obstetricians and Gynecologists responded to the FDA’s announcement by reaffirming that acetaminophen remains “the analgesic and antipyretic of choice during pregnancy.” ACOG’s position is that the current weight of evidence does not support a causal link and that no change in clinical practice is warranted. Their standing advice is to use the lowest effective dose for the shortest necessary duration.
The European Medicines Agency reached a similar conclusion after reviewing the available studies in 2019, finding the results “inconclusive” and stating that no link with neurodevelopmental disorders could be established. Prescribing guidance across the EU remained unchanged.
The Litigation Picture
Thousands of lawsuits have been consolidated into a multidistrict litigation case in the Southern District of New York, with parents alleging that prenatal acetaminophen exposure caused their children’s autism or ADHD. However, a federal judge excluded the plaintiffs’ expert testimony in December 2023, ruling that the scientific evidence did not meet the standard required for admissibility. A second motion to exclude expert opinions was granted in July 2024. Without admissible expert testimony connecting the drug to the diagnoses, the plaintiffs face a significant legal barrier.
Putting the Risk in Perspective
An estimated 65 percent of pregnant women in the United States use acetaminophen at least once during pregnancy. If the drug were a meaningful cause of autism, the signal would likely be far clearer in sibling studies and controlled analyses than it has turned out to be. The fact that the association vanishes when researchers control for family-level factors is a strong indicator that confounding, not the drug, explains the pattern.
That said, the general principle of minimizing any unnecessary medication during pregnancy still applies. If you have a mild headache or a low-grade fever that you can manage with rest and fluids, skipping the pill is a reasonable choice regardless of any autism question. When pain is significant or a fever climbs high enough to pose its own risks to the pregnancy, acetaminophen remains the option with the most established safety profile. The practical takeaway is straightforward: use it when you need it, skip it when you don’t, and keep the dose and duration as low as the situation allows.