Monday, August 22, 2016

Harris' "How Big A Risk Is Acetaminophen During Pregnancy?"

This study, which found a link between maternal Tylenol usage during pregnancy and ADHD, has been making the rounds, particularly in the Academic Mama circles I move in.

Being pregnant is hard. For just about every malady, the only solution is to stay hydrated. With a compromised bladder.

But at least pregnant women have Tylenol for sore hips and bad backs. For a long time, this has been the only safe OTC pain reliever available to pregnant women. But a recent research article has cast doubt on this advice.

A quick read of this article makes it sound like you are cursing your child with a lifetime of ADHD if you take Tylenol. And this article has become click-bait fodder.

But these findings have some pretty big caveats. Harris published this reaction piece at NPR. It is a good teaching example of media hype vs. incremental scientific progress and the third (or fourth or fifth) variable problem. It also touches on absolute vs. relative risk. NOTE: There are well-documented concerns about Tylenol and liver damage. Also, more recent studies question its effectiveness, but those are teaching examples for another day.

Getting back to the current study: If you account for prenatal smoking, drinking, and pre-existing maternal psychiatric problems, the ADHD:Tylenol effect is either greatly weakened or goes away entirely.

And even if you don't account for those co-variates, the actual change that the study found was small. From the article:
It turns out you can't answer that question fully by reading the paper alone. You have to dig into the supplementary data tables posted online. The 20 percent to 45 percent increase is actually a small change. To pick one representative endpoint: Among women who had not taken the drug, 4.3 percent of their children registered an elevated score on the "SDQ total difficulties" test. Compare that with 6.3 percent of children born to women who did take the drug.

How to use in class:
-Absolute risk versus relative risk.
-Covariates.
-Crap science reporting.
-Introducing the topic of how hard it is to do medical research on pregnant women. No IRB under the sun would approve you to do a double blind study on anything that would potential damage a fetus or mamma! Hence, limited real knowledge on best practices for pregnant women until the shit hits the fan (see Accutane).

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