• Autism diagnoses have increased ~5× since 2000, largely due to broader diagnostic criteria and greater awareness, not a single new cause.

• Current evidence does not show a causal link between acetaminophen (Tylenol) use in pregnancy and autism; the observed associations are weak and often disappear when controlling for family genetics and home environment.

• Even if a small effect existed, the absolute risk increase is tiny (~0.09%).

• Genetics (80–90%) drive most autism risk; other contributors include older parental age, maternal metabolic health, prematurity, and pollution.

• In pregnancy, untreated fever can pose greater risk to the fetus than appropriate, short-term acetaminophen use. Always discuss with your doctor.

Many studies have looked for a link between prenatal acetaminophen use and autism. Here’s the big picture:

• Large population studies show small correlations (around a 5–6% relative increase).

• When researchers compare siblings (same genetics and home), the association disappears—suggesting confounding factors, not causation.

• Smaller studies showing stronger signals often have weak exposure measures, recall bias, or selection issues.

Bottom line: A consistent causal link has not been demonstrated. If any risk exists, it appears very small.

Doctors often use the Bradford Hill criteria—a nine-point framework to test causality. Applied to acetaminophen and autism:

• Strength of effect: Weak (about 5% relative risk).

• Consistency: Mixed to moderate.

• Specificity: Weak (many other, stronger autism risks exist).

• Temporality: Yes (drug use precedes diagnosis).

• Dose-response: Inconsistent.

• Plausibility & coherence: Unclear; animal data inconsistent.

• Analogy: Not supportive (some evidence suggests the opposite pattern with other prostaglandin inhibitors).

Takeaway: These criteria do not support a causal conclusion.

Two main reasons:

1. Expanded diagnostic criteria and awareness (accounts for a large share of the increase).

2. Population trends: higher parental age, more prematurity/early term births, and maternal metabolic issues.

Additional contributors include air pollution and other environmental factors. Even if acetaminophen played any role, it would likely be minor compared to these.

• For minor aches, try non-drug strategies first (rest, hydration, ice/heat as advised by your doctor).

• For significant pain or fever, acetaminophen is generally preferred in pregnancy when needed and used as directed.

  • Why? Untreated fever—especially early in pregnancy—has clearer links to adverse outcomes than short-term, appropriate acetaminophen use.

  • NSAIDs (e.g., ibuprofen) may be used early in pregnancy under guidance but are not recommended in the 3rd trimester.

  • Opioids carry greater risks and are typically avoided unless absolutely necessary and closely supervised.

Always follow your provider’s instructions on dosing and duration.

Benefits

• Helps control fever (reducing fetal risk from maternal hyperthermia).

• Offers safer first-line pain relief option in pregnancy versus many alternatives.

Considerations

• Use the lowest effective dose for the shortest time.

• Combine with non-pharmacologic supports when possible.

• Discuss your full medication/supplement list with your provider.

• Focus on modifiable health factors with bigger impact: healthy nutrition, glucose and lipid control, adequate sleep, stress, and prenatal care.

• Physician-led, family-run practice with 35+ years serving Queens.

• Board-certified doctors, bilingual care (English/Español), and a safety-first approach.

• Coordinated care with your OB-GYN for evidence-based, personalized guidance during pregnancy.

You may also be interested in related reading on our site, such as hormone health, weight-management programs, and wellness support for pregnancy planning (ask our team for the best resources on levamedical.com).