Autism prevalence of 1 in 31 and the federal announcements: what BCBAs and RBTs can tell families

The CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network reported that among 8-year-olds in 2022, 32.2 per 1,000 children, about 1 in 31, had been identified with autism across 16 sites¹. The figure ranged from 9.7 per 1,000 in Laredo, Texas, to 53.1 in California, and autism was 3.4 times as common in boys as in girls¹.

ADDM is an active surveillance program: it estimates prevalence and characteristics and tracks when children are identified¹. A child counts if records show an autism diagnosis in a comprehensive evaluation, special education eligibility for autism, or an autism diagnostic code¹. The network has published estimates every two years since 2000, when the figure was 1 in 150; in 2020 it was 1 in 36¹.

The report, published on April 17, 2025, concludes that autism prevalence among 8-year-olds increased from 2020 to 2022, and that differences over time and across sites can reflect evaluation and identification practices and the requirements that affect access to services¹. It adds that research has not shown that living in certain communities raises a child’s risk, and that differences between communities may come from the availability of early detection and evaluation services and from diagnostic practices¹.

Two other findings fit that reading, according to the report itself:

• Prevalence was higher among Asian or Pacific Islander, Black and Hispanic children than among White children, a reversal the report calls consistent with more access to identification in previously underserved groups¹.
• Identification by 48 months was 1.7 times as high among children born in 2018 as among those born in 2014, which the report reads as more early identification, consistent with historical patterns¹.

The report also sets its own limits. Its 16 sites are not nationally representative, and its sources generally exclude private schools and primary care providers¹. It counts identified children; it does not study what causes autism. Federal officials describe the trend in different terms: announcing the leucovorin action, the FDA Commissioner spoke of “a tragic four-fold increase in autism over two decades”⁴.

On September 22, 2025, two agencies of the Department of Health and Human Services, the FDA and the NIH, made three announcements²⁵:

• Acetaminophen. The FDA initiated the process for a label change to reflect evidence suggesting that use of acetaminophen by pregnant women may be associated with an increased risk of autism and ADHD². Commissioner Marty Makary said “the choice still belongs with parents” and that it remains reasonable to use acetaminophen in certain scenarios². The FDA’s notice to physicians says an association has been described in many studies, but “a causal relationship has not been established” and there are contrary studies³. It asks clinicians to consider minimizing use for routine low-grade fevers, and notes that acetaminophen is the safest over-the-counter option in pregnancy, while aspirin and ibuprofen have documented adverse effects on the fetus³.
• Leucovorin. The FDA initiated the approval of leucovorin calcium tablets for cerebral folate deficiency, a condition in which developmental delays with autistic features have been observed⁴. For a broader group with autistic features and folate receptor autoantibodies, the FDA wrote that “there are limitations on the available data” and that more studies are needed⁴.
• Research. The NIH launched the Autism Data Science Initiative, with more than $50 million for 13 projects on the causes and rising prevalence of autism⁵. Its release says research has shown a strong genetic component, while nongenetic factors such as environmental exposures are less well understood⁵.

On March 10, 2026, the FDA approved expanded use of Wellcovorin (leucovorin calcium) tablets for cerebral folate deficiency in patients with a confirmed variant in the FOLR1 gene⁶. The label limits the new indication to that genetic condition, calls it very rare and states that no clinical trials have been conducted; the evidence came from 46 patients in 26 published case reports and case reviews⁷. The Commissioner said the approval may benefit some people with this deficiency who have developmental delays with autistic features⁶.

Separately, on January 29, 2026, the European Journal of Pediatrics retracted a randomized, placebo-controlled trial of folinic acid, another name for leucovorin, in autistic children, published in September 2024. A statistical review could not replicate its results, and the editor no longer has confidence in its conclusions⁸.

The studies do not all point the same way, and study design matters:

• A 2025 review using the Navigation Guide method concluded that the evidence is consistent with an association, said observational limitations preclude definitive causation, and recommended judicious use under medical guidance rather than a broad limit⁹.
• A 2026 meta-analysis in The Lancet Obstetrics, Gynaecology & Women’s Health included 43 studies in its review and 17 in its meta-analysis, limited to sibling comparisons¹⁰. Among siblings, exposure in pregnancy was not associated with autism (odds ratio 0.98), ADHD (0.95) or intellectual disability (0.93)¹⁰. The authors also cite a Swedish cohort of 2.48 million births in which sibling comparisons showed no increased likelihood of autism¹⁰.
• A 2025 BMJ umbrella review of 9 reviews found that the reviews reported possible to strong associations, but its authors rated confidence in those reviews as low to critically low¹¹. Sibling-controlled analyses adjust for family factors and unmeasured confounding, and in them the increased risk seen in whole cohorts did not persist; the authors conclude that existing evidence does not clearly link the two¹¹.

Parents may ask whether a medicine caused their child’s autism or whether to try leucovorin. Those are medical questions, and the ethics codes point to referral¹²¹³:

• BCBAs practice only within their scope of competence and otherwise refer (1.05); they make sure medical needs are assessed when medical variables may be involved, and document the referral and follow up (2.12); and they use understandable language (2.08)¹².
• Public statements must be truthful, not misleading and based on existing research, and the Code counts social media among them; no specific advice about a client’s needs in public forums (5.03)¹².
• RBTs work in a clearly defined role under close supervision (1.03), tell their supervisor when asked to go beyond their certification or competence (1.06), take caregivers’ questions to the supervisor (2.06) and make no misleading statements about their services (1.05)¹³.

A neutral answer can be as simple as this suggestion of ours: “The CDC number counts children identified with autism; it is not a study of causes. The FDA says a causal link with acetaminophen has not been established. Your doctor is the right person for medicine decisions.”

• The 1 in 31 figure comes from 2022 data in the April 2025 report; ADDM publishes every two years¹.
• The FDA started the acetaminophen label process in September 2025². As of October 16, 2026, we did not find an FDA document confirming that the change is complete, so check the current label before repeating any claim about it.
• The leucovorin label lists two indications: reducing the toxicity of methotrexate in adults with impaired elimination or of folic acid antagonists after an overdose, and, since March 2026, cerebral folate deficiency with a confirmed FOLR1 variant⁶⁷.

This article is not medical advice. It explains what the agencies and studies say so that you can answer within your role and point families to their physicians.