This is the first of a series on how Oster is wrong on drinking in pregnancy in her 2013 book Expecting Better: Why the Conventional Pregnancy Wisdom is Wrong and What You Really Need to Know.

For this part, we'll focus on how and why her biological model of ethanol metabolism is incorrect. This premise forms part of her argument on why it's acceptable to drink 1-2 drinks* a week in the first trimester and more later in pregnancy.

Oster writes,

To understand why there is a difference between excessive drinking and moderate or light drinking, it's useful to think a little bit about how the biology works. Many women seem to think that when they drink, that glass of wine is channeled directly to the fetus. People correctly note that you would not give your infant a glass of wine, so why would you give your fetus one? Needless to say, this is not really how it works. When you drink, alcohol enters your digestive system and is passed into your bloodstream. Your liver processes the alcohol into a chemical called acetaldehyde and then into acetate. The acetaldehyde is toxic to other cells, and depending on how [...]

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Outline:

(05:10) Steel-manning the maternal acetaldehyde hypothesis

(13:03) The Bottom Line

(14:07) Footnotes

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First published:
August 6th, 2026

Source:
https://www.lesswrong.com/posts/Anuec5i3AGkovRu3C/contra-oster-on-alcohol-in-pregnancy-part-1-the

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Narrated by TYPE III AUDIO.

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“Contra Oster on Alcohol in Pregnancy. Part 1. The pharmacokinetics of alcohol metabolism” by Mvolz

LessWrong (30+ Karma)

“Contra Oster on Alcohol in Pregnancy. Part 1. The pharmacokinetics of alcohol metabolism” by Mvolz