What Americans Really Believe Causes Autism and Pregnancy Risks — The Results Will Surprise You

When scientists describe the causes of autism today, they use cautious, complex language: a mix of genetic factors and environmental exposures that interact during early brain development. But what ordinary Americans believe — what parents read on social media, what gets repeated at kitchen tables and in comment threads — doesn’t always match the scientific consensus. And those beliefs matter. They shape what people do during pregnancy, whether they vaccinate their children, and how they judge public-health guidance.

Below, we unpack the latest surveys and reporting to reveal who believes what, why misinformation keeps spreading, and what the medical community is doing (and not doing) about it. The results are sobering — and, in some ways, surprising.

The headline numbers (the surprising part)

• A meaningful slice of Americans still think vaccines are linked to autism. Different polls show different figures depending on question wording and timing, but several recent surveys find roughly one-in-seven to one-in-four adults either endorse the claim that MMR (measles–mumps–rubella) or childhood vaccines cause autism or express uncertainty about it. That figure is higher in some subgroups and lower in others.
• Confidence that childhood vaccines are beneficial remains high overall, even while doubts about specific links persist. For example, major surveys find most Americans still say the benefits of MMR outweigh the risks — but worry and uncertainty about particular vaccines (or vaccine timing) rose in the wake of high-visibility misinformation.
• Pregnancy-specific beliefs have become a flashpoint. Very recently (September 2025), U.S. federal officials and media coverage focused public attention on a possible link between acetaminophen (Tylenol) use in pregnancy and autism. That announcement — and rapid pushback from scientific bodies — has amplified public confusion and brought pregnancy-drug risk beliefs into the spotlight. Global health agencies immediately cautioned that the evidence is not definitive and that pregnant people should consult clinicians rather than avoid needed treatment.
• Pregnant people and parents show real hesitancy about vaccinating in pregnancy and vaccinating their infants. Multiple surveys show lower confidence in vaccine safety for pregnant people than for adults generally, and some research suggests only a minority of pregnant people currently plan to fully vaccinate their children on the recommended schedule.

Those are the topline facts. Now let’s dig into the background, the reasons, and the consequences.

Where the vaccine–autism myth came from — briefly

The idea that vaccines cause autism traces to a small, now-discredited 1998 paper that suggested a link between the MMR vaccine and autism. That paper was retracted, and subsequent large, carefully controlled studies worldwide found no credible link between vaccines and autism. Public-health bodies — the CDC, WHO, and major medical societies — continue to state that vaccines do not cause autism. Nonetheless, the original claim took deep root because it touches on parental anxiety, coincides with the age when autism is often diagnosed, and was amplified by media and later social media.

Why does that old myth persist? Because belief isn’t only about evidence. It’s about emotion, trust, and narrative. Vaccines are given to healthy children; any unfortunate developmental change that shows up afterward feels causally linked in the human mind. Add loud online communities, targeted misinformation, and eroding trust in institutions — and the myth finds new life. Evidence alone rarely vanquishes a story that feels intuitively plausible.

The state of public belief: nuance matters

Saying “a quarter of Americans believe vaccines cause autism” is an oversimplification. Polls vary by exact question wording, timing, and audience. For example:

• Some large polls found roughly 24% of adults said the MMR vaccine causes autism or were unsure — a strikingly high fraction that underlines persistent doubt. Other surveys show smaller but still notable minorities endorsing the claim.
• Other research by Pew and large polling bodies finds that most Americans (around 80–90%) continue to think the benefits of childhood vaccines outweigh the risks, especially for classic childhood vaccines like MMR. That tells us belief is not binary: many people can say vaccines are generally beneficial while still harboring anxiety about specific outcomes or ingredients.
• Among parents and pregnant people, beliefs are more conflicted. Confidence in certain vaccines (e.g., flu, COVID-19) and in vaccine safety during pregnancy is lower than overall vaccine confidence, reflecting how pregnancy and infancy are emotionally charged contexts where risk tolerance shifts.

Translation: most Americans accept “vaccines are good,” but sizable minorities are uncertain about specific vaccine–autism claims — and that uncertainty shapes behavior.

Pregnancy risks: the Tylenol (acetaminophen) debate and other misconceptions

Pregnancy is another area where confusion thrives. For decades, public-health guidance has emphasized avoiding alcohol and certain medications in pregnancy, while noting that some medications (like acetaminophen) are commonly used when the benefit outweighs the risk. Recent headlines have changed that conversation quickly:

• In September 2025, U.S. officials signaled they would limit advice around acetaminophen during pregnancy and opened a process to review labeling — a move that created a media storm and public anxiety. Major health organizations and the WHO responded by saying the evidence is inconsistent and that pregnant people should not make unilateral medication changes without talking to clinicians.
• Separate from acetaminophen, the public has long been uncertain about vaccines in pregnancy (e.g., flu, Tdap, COVID-19). Surveys show many adults and pregnant people have lower confidence in vaccine safety during pregnancy than for adults in general. That uncertainty affects uptake: influenza and Tdap vaccine coverage among pregnant people remains incomplete, and intention to vaccinate infants varies.
• Alcohol during pregnancy remains a known risk with clearer public messaging, yet surveys and population data show that a nontrivial minority of pregnant people report drinking, including binge drinking in certain surveys — an ongoing public-health problem.

So the “surprise” is twofold: (1) new, headline-grabbing claims (like acetaminophen links) can shift beliefs quickly even when data are mixed, and (2) for many pregnancy risks, the public remains uncertain despite decades of guidance.

Why misinformation spreads — and who’s most susceptible

Research on belief formation shows a few consistent drivers:

• Timing and plausibility: Autism symptoms often appear at ages when children receive multiple vaccines, making temporal coincidence feel causal.
• Emotional salience: Pregnancy and child health are deeply emotional subjects. Emotional narratives beat dry data at getting attention.
• Information ecosystems: Social media algorithms reward engagement, which often means sensational claims get amplified. Influencers, political actors, and fringe medical voices have amplified doubts about vaccines and pregnancy safety on multiple platforms.
• Distrust in institutions: Americans who distrust government, medicine, or big pharma are likelier to accept alternative explanations. When political leaders or media figures highlight a claim, even tentatively, it can move public opinion quickly. Recent high-profile statements about acetaminophen and autism are a case in point.
• Knowledge gaps: Polling shows many people are simply unsure about the right answers, which leaves space for persuasive misinformation to fill the void.

Consequences: from delayed vaccines to risky pregnancy choices

Beliefs shape actions. The available data show real-world impacts:

• Some parents delay or decline vaccines for their children because of safety worries. Recent polls found that a noticeable share of parents have delayed or skipped vaccinations for reasons ranging from concerns about necessity to fear of side effects. That behavior can lower community immunity and increase the risk of outbreaks.
• Pregnant people hearing conflicting messages may either avoid needed treatments (e.g., untreated fever is dangerous) or avoid recommended vaccinations (like flu or Tdap), both of which can have harmful effects. Public-health experts worry that high-profile, scientifically weak claims can reduce uptake of life-saving interventions.
• At a systems level, persistent public uncertainty erodes trust in health guidance and complicates the job of clinicians, who must correct misinformation in time-constrained appointments.

What the science actually says (short version)

• Vaccines and autism: The large, well-designed body of epidemiological research finds no credible link between childhood vaccines (including MMR) and autism. Major health authorities — CDC, AAP, WHO — are emphatic on this point.
• Acetaminophen in pregnancy: Some observational studies have reported associations between prenatal acetaminophen exposure and neurodevelopmental outcomes (e.g., ADHD, autism) in children. Observational studies can show associations but cannot prove causation because of confounding factors. Regulatory and health bodies are assessing the evidence; some have urged caution in routine, nonessential use but stop short of blanket prohibition. Clinicians generally advise pregnant people to consult their providers before stopping needed medications. The scientific picture is evolving.
• Alcohol and pregnancy: Alcohol is a well-established teratogen at sufficient exposure levels; guidelines recommend abstaining from alcohol during pregnancy because no safe threshold has been established for some outcomes. Yet population surveys show ongoing consumption in a subset of pregnancies.

How to talk about this (for parents, clinicians, communicators)

If you’re a parent or pregnant person:

• Ask your clinician. Your obstetrician, midwife, or pediatrician can walk through risks and benefits in the context of your health history.
• Don’t make choices based on a single headline. Science evolves; one study is seldom definitive.
• Balance risks: sometimes taking a medication is safer than letting a high fever or untreated condition persist.

If you’re a clinician or public-health communicator:

• Start with empathy. People who were harmed or scared by medical experiences are not persuaded by condescension.
• Use clear, concrete examples (e.g., “Large studies of X people found no association”) but also acknowledge uncertainty where it exists.
• Anticipate misinformation and address it directly, explaining why a particular claim (like vaccines cause autism) is not supported by the totality of evidence.

If you’re a journalist or editor:

• Contextualize single studies. Include expert reaction and prior evidence.
• Avoid sensational headlines that imply causation when a study only shows association.

Why these beliefs aren’t just “wrong” — they’re human

It’s easy to write off people who doubt vaccines or worry about pregnancy risks as irrational. But that’s not the whole story. Beliefs form where emotion, lived experience, and institutional trust intersect. Parents are trying to protect their children in a world where scientific reports feel distant and technical. When a claim about causes or risks offers a clear action (stop the shot, avoid the pill), it becomes psychologically attractive even if the evidence is weak.

Changing beliefs requires more than broadcasting facts. It requires better conversations, accessible explanations, and trusted voices — clinicians, community leaders, and peers — who can bridge the gap between data and daily life.

The bottom line: proceed with evidence, not panic

The surprising part of recent public polling and the media cycle is not only that doubts persist — it’s how quickly those doubts can expand when amplified by leaders or trending headlines. Most Americans continue to say vaccines are beneficial. Yet nontrivial minorities either doubt the vaccine–autism consensus or feel uncertain about pregnancy safety for specific substances. That uncertainty translates into real behavior: delayed or skipped vaccines, confusion about medication use in pregnancy, and hesitancy about recommended maternal immunizations.

If you’re a parent or pregnant person reading the headlines, the best immediate step is simple: talk to a trusted clinician, ask for evidence in plain language, and weigh the harms of action vs. inaction. If you’re a communicator or policymaker, recognize that facts alone are not enough — you must meet people where they are, explain clearly, and build trust.