The Science Baby

Last week, a certain loudmouth in America told pregnant people to stop taking paracetamol (or “acetaminophen” or “Tylenol,” pick your flavour, they’re all the same thing), claiming it might cause autism in their kids. That advice set off alarm bells everywhere.

Expectant mothers have long been told that paracetamol is one of the safest over-the-counter options for managing pain or fever during pregnancy. But now that single “safe” drug is getting dragged into a storm of fear. Some mothers whose children are autistic may feel guilt or anxiety that a past choice “caused” their child’s autism. And preganant women are left feeling like they ahhve to suffer in order to keep their baby safe. So it’s no wonder this claim has stirred up so much worry.

So let me lay out what the evidence actually says. And spoiler alert: he’s probably talking out of his bum.

Two studies fueling the fear

Trump and his cronies’ announcement leaned heavily on two sources:

1. A 2019 study that measured breakdown products of acetaminophen in umbilical cord blood, and which found an association between higher levels and later autism diagnoses.
2. A more recent 2025 review that looked at 46 observational studies, of which 27 claimed to find positive associations between prenatal acetaminophen use and autism in kids.

Superficially, that sounds scary. But, importantly, not all evidence is created equal.

Observational vs causal: what the difference is

The 2025 review was based entirely on observational studies. So they’re not experiments taking place in controlled settings. Instead, researchers looked back at what’s happened in real life (like who took what drug, and who developed autism) and searched for statistical associations. Those studies can suggest correlation, but they cannot prove causation.

Think of it like this:

It’s known that ice cream sales and shark attacks both go up in summer. But that doesn’t mean eating ice cream causes shark attacks. Instead, there’s a lurking third variable (summer heat, more people swimming) that’s driving both.

In the same way, paracetamol use might co-occur with something else or several something-elses that are the real causal factors.

A more robust study that poops on the “causal link” hypothesis

The Trump announcement focused on studies that supported their conclusions, regardless of their strengths and weaknesses.

But it’s not like this is the only research out there, and one study in particular was notably absent.

A Scandinavian study in 2024 looked at nearly 2.5 million children, to specifically search for links between autism disorders and mothers who used acetaminophen during pregnancy.

Critically, they used sibling comparisons, which keep many genetic and environmental influences that siblings share (parental traits, household, early life) constant. If one sibling was exposed to the drug and the other wasn’t, but both otherwise grew up in the same family, that helps isolate the “drug effect” more cleanly.

And in those analyses, the researchers found no increased risk of autism once you account for shared familial factors.

That strongly suggests that the associations found in the observational work were in fact confounded by family-level factors.

Why “positive” associations deserve a second glance

Here’s a hypothesis that fits both the data and plausibility:

• Autism is known to have strong heritability, which means it tends to be carried in the genes more than it’s influenced by outside factors.
• Autistic (and neurodivergent in general) individuals may experience bodily discomfort more acutely, especially during pregnancy. So things like headaches, inflammation, pain may be felt more intensely.
• Therefore, pregnant autistic people, or those carrying genes associated with autism, might be more likely to reach for paracetamol for relief.
• The child then inherits autism-related genetic risk (as is common in many autism cases), making it look like paracetamol use is correlated with autism but causality runs the opposite way.

In short: paracetamol use might be a consequence of underlying traits or predispositions, not the cause of autism.

What health authorities currently advise

• The American College of Obstetricians and Gynecologists (ACOG) reaffirmed that acetaminophen remains the safest first-line option for pain and fever in pregnancy, and that current data do not support a causal link to neurodevelopmental disorders.
• In the European Union, regulatory agencies say that there is no new evidence requiring changes to pregnancy-use guidelines for paracetamol, and that it remains an important option for pain or fever when needed.
• The World Health Organization has stated that the evidence of a link is “inconsistent,” noting that while some observational studies suggest associations, many others find no relationship.

So globally, expert consensus continues to support the moderate use of paracetamol in pregnancy, with no evidence of ill effects.

What to do if you’re pregnant and feeling worried

1. Don’t panic. Claims of causation are not supported by high-quality evidence.
2. Talk to your clinician. If you have pain, fever, or discomfort, get personalized guidance. Untreated fever or severe pain itself can carry risks for both mother and fetus.
3. Use the lowest effective dose for the shortest possible time if you do use paracetamol, and only when clinically indicated.
4. Explore non-drug strategies where possible (rest, hydration, thermal measures) but don’t feel guilty about medication when it’s needed.
5. If you have a family history of autism or neurodivergence, bring that up with your provider, as it might guide extra monitoring, but doesn’t imply causality via drugs.

Final verdict: safe, but science continues

Here’s where I stand (science baby hat firmly on):

• Paracetamol is still, by far, one of the safest drugs to relieve pain and fever in pregnancy.
• Observational associations between prenatal paracetamol use and autism exist in the literature, but they are weak, inconsistent, and likely confounded by other factors.
• The objectively stronger research (sibling comparisons, large cohorts) show no evidence of an independent causal effect.
• So a more plausible explanation for the link is reverse causality or confounding genetic factors.
• Until there is much stronger evidence, we should not throw out paracetamol as a tool for managing pain and fever during pregnancy.

So to all you expectant mamas: you’re probably fine. Don’t let orange people with loud opinions make you feel like your past choices doomed your child. Paracetamol remains a perfectly reasonable option when needed, and there’s no credible evidence right now that it will harm your child’s neurodevelopment.