Several studies have found a statistical association between acetaminophen use during pregnancy and autism in children, but the largest and most rigorous research to date has not confirmed a causal link. The topic is genuinely unsettled, with major health authorities currently offering different levels of concern. Here’s what the evidence actually shows and what it means in practical terms.
What the Largest Study Found
A 2024 study published in JAMA analyzed data from more than 2 million children in Sweden and concluded that acetaminophen exposure during pregnancy is not linked to the risk of developing autism, ADHD, or intellectual disability. This is the largest study on the question to date, and its design addressed a critical weakness in earlier research: it compared siblings, some of whom were exposed to acetaminophen in the womb and some who were not. Sibling comparisons help control for genetics and family environment, two factors that heavily influence autism risk. When those factors were accounted for, the apparent connection between acetaminophen and autism disappeared.
Earlier, smaller studies had reported associations between prenatal acetaminophen use and neurodevelopmental conditions. Some of those studies suggested that longer durations of use carried higher risk. But most relied on mothers recalling their medication use months or years later, and none could fully separate the effect of acetaminophen from the effect of the conditions it was being used to treat.
The Confounding Problem
This is the central challenge in this research: pregnant people take acetaminophen because they have fever, pain, or infection. Those underlying conditions themselves can affect fetal brain development. High maternal fever, in particular, is a known risk factor for neurodevelopmental problems. So when a study finds that children whose mothers took acetaminophen have slightly higher rates of autism, it’s genuinely difficult to determine whether the drug caused the outcome or whether the fever or illness that prompted its use was the real factor.
ACOG, the main professional organization for obstetricians in the United States, has emphasized this point directly: failing to treat conditions like maternal fever can create severe risk of harm or death for both the pregnant person and the fetus. Avoiding acetaminophen out of precaution but leaving a high fever untreated could be more dangerous than taking the medication.
Where Medical Authorities Currently Stand
This is where things get complicated, because two major U.S. health authorities are sending somewhat different signals.
ACOG reaffirms that acetaminophen remains the pain reliever and fever reducer of choice during pregnancy. Their position, updated in 2025, states plainly: “The current weight of evidence does not support a causal link between prenatal acetaminophen use and neurodevelopmental disorders.” They recommend no change in clinical practice, while advising the standard approach of using the lowest effective dose for the shortest necessary duration.
The FDA, however, initiated a label change process for acetaminophen products to reflect evidence suggesting a possible association with neurological conditions like autism and ADHD in children. FDA Commissioner Marty Makary stated the agency was acting on “a considerable body of evidence about potential risks,” while also acknowledging that a causal relationship has not been established and that contrary studies exist in the literature. The FDA noted that the choice remains with parents and that acetaminophen use remains reasonable in certain scenarios during pregnancy.
The FDA also pointed out a practical reality: acetaminophen is the only over-the-counter medication approved to treat fevers during pregnancy. Aspirin and ibuprofen both have well-documented adverse effects on the fetus, making them unsuitable alternatives for most of pregnancy.
What Animal Research Shows
Laboratory studies in animals have identified several ways acetaminophen could theoretically affect fetal development. In animal models, prenatal exposure altered sex hormone levels in both mothers and fetuses, inhibited the development of connections between brain cells in the hippocampus (a region important for learning and memory), and caused visible changes in fetal brain, bone, and kidney tissue. These studies use controlled doses and can isolate the drug’s effects in ways human studies cannot.
However, animal studies don’t automatically translate to human risk. The doses used, the timing of exposure, and the biology of the species all differ. What these studies do provide is a plausible biological explanation for how acetaminophen could affect brain development, which keeps the question scientifically open even as the strongest human data has been reassuring.
What This Means If You’re Pregnant
The practical takeaway is nuanced. The best human evidence currently available, including the 2-million-child Swedish study, does not support a causal link between acetaminophen and autism. At the same time, the FDA has decided the totality of evidence warrants informing patients about a possible association, even without proof of causation.
Both sides agree on the general principle: use acetaminophen when you genuinely need it, at the lowest dose that works, for as short a time as possible. This has always been standard guidance for any medication during pregnancy. Neither ACOG nor the FDA recommends avoiding acetaminophen entirely, and both note that untreated fever and pain carry their own serious risks. There are no safer over-the-counter alternatives for fever reduction during pregnancy.
If you’re taking acetaminophen occasionally for a headache or short-term fever, the current evidence suggests that is unlikely to pose a meaningful neurodevelopmental risk to your child. If you find yourself needing it frequently or for extended periods, that’s worth discussing with your provider, both to address the underlying condition and to weigh the benefits and uncertainties of continued use.