[ben30]

The political circus is drowning out some pretty clear science here. Let me break this down without the academic jargon:

The basic problem: Most studies can't tell the difference between the medicine and why you're taking it. If you're having Tylenol during pregnancy, it's probably because you have a fever, infection, or severe pain. Guess what also increases autism risk? Fever, infections, and severe illness.

What makes the Swedish study special: They compared siblings in the same family. Same genes, same environment, same parents - but one child was exposed to acetaminophen in the womb and the other wasn't. This controls for all the family-level stuff that usually confuses these studies.

The numbers tell the story: - Regular studies: "5% increased autism risk with acetaminophen" (HR 1.05) - Swedish sibling comparison: "Actually, no increased risk" (HR 0.98, could be 7% protective to 4% harmful - basically noise) - Meanwhile, untreated fever: 40% increased risk, multiple fevers: 212% increased risk

We have evidence that fever during pregnancy messes with fetal brain development. We have the best study ever done showing acetaminophen doesn't cause autism. So we're going to... stop treating the fever?

It's like refusing to use a fire extinguisher because you're worried it might stain your carpet, while your house burns down.

The Swedish study should have ended this debate. When the science is done correctly, the acetaminophen "risk" vanishes completely.

Sources:

- Swedish study: https://jamanetwork.com/journals/jama/fullarticle/2817406

- Fever-autism evidence: https://molecularautism.biomedcentral.com/articles/10.1186/s...

[Ancapistani]

> The Swedish study should have ended this debate.

I agree with everything you’ve said except this statement.

I’m of the opinion that a single study should never end debate. It may inform policy, sure, but no end debate. Certainly not unless and until it has been replicated by others.

[ben30]

Fair point on the "ended debate" phrasing - that was imprecise on my part. What I should have said is "the Swedish study provides the strongest evidence to date and shifts the burden of proof." It's not actually a single study though. The pattern is consistent across study quality levels:

Population studies (many): Small associations, but can't control for confounding

Negative control studies (several): Associations weaken when using better controls

Sibling studies (multiple, including Swedish): Associations disappear entirely

Meanwhile, fever studies (dozens): Consistent risk signals across different populations

The Swedish study is just the largest and best-designed in a hierarchy of evidence that all points the same direction. When you see this "dose-response by study quality" pattern - where better methodology consistently yields weaker effects - it's usually a strong signal that the original association was artifactual.

The Economist piece published yesterday reinforces this. They mention the NIH study of 200,000 children that "found no link at all" - that's another high-quality study reaching the same conclusion. Meanwhile, the studies showing associations (Nurses' Health Study II, Boston Birth Cohort) are exactly the type of population studies that can't control for the fever/infection confounding.

Science is never "settled" in an absolute sense, but the weight of evidence here is pretty clear. We're not waiting for more acetaminophen studies - we're ignoring the ones we already have while making policy based on weaker evidence.

That's the real problem with the current policy shift.

[Ancapistani]

> Fair point on the "ended debate" phrasing - that was imprecise on my part.

Oh, no worries. I was fairly certain I understood what you meant. Honestly that part of my comment was intended for others reading it, as it certainly seems that many people do believe a single peer-reviewed study should end the debate.

> the Swedish study provides the strongest evidence to date and shifts the burden of proof

100% agree :)

> It's not actually a single study though.

Unless I'm missing something, it is. It looks at a single population (Swedish children born between 1995 and 2019) that is divided into multiple cohorts. This approach strikes me as entirely valid -- but it also weakens the strength of the signal that it provides. With a population of this size and number of recorded attributes, there are likely cohorts that could be found to support any hypothesis the author would like. There are almost certainly many that would meet the bar of statistical significance if you're willing to form the hypothesis based on the data.

In other words, my initial impression is that it's potentially a variant of "P-hacking", regardless of intent. Unless the hypothesis was formed a priori, recorded, and not modified the results are evidence that a pattern may exist but not proof that it does.

> The Swedish study is just the largest and best-designed in a hierarchy of evidence that all points the same direction

From my perspective -- and to be clear, that's very much a lay perspective! -- I agree, and that direction is "there is likely a correlation between the use of acetaminophen during pregnancy and childhood autism diagnosis".

... but at the risk of being tiresome, correlation is not causation. My (unproven!) hypothesis at this point is that both higher rates of autism and acetaminophen use are a result of persistent fevers, which itself is likely a result of chronic systemic inflammation.

If that is in fact the case, then it would simultaneously be true that acetaminophen use would be a strong leading indicator of autism and that ceasing the use of acetaminophen during pregnancy would actually _increase_ the rate of autism overall.