Expecting Better Fish Chart: Fish to Eat When Pregnant

This article is an excerpt from the Shortform summary of "Expecting Better" by Emily Oster. Shortform has the world's best summaries of books you should be reading.

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Which fish are best for you to eat during pregnancy? In Expecting Better, Emily Oster covers the best fish while pregnant, from best to worst.

First, let’s review. Fish have two competing effects on the fetus:

  • High mercury lowers IQ.
    • A 1 ug/g increase in mercury sampling causes a decrease of 0.7 IQ points. In other words, the average American woman and the highest mercury-exposed woman produces a 3.5 IQ point difference in kids.
    • Predator fish and long-living fish (listed below) have the highest levels of mercury. The former eats other fish harboring mercury, and the latter accumulates mercury over a long lifetime.
  • Omega-3 fatty acids increase IQ.
    • Increasing DHA fatty acids by 1 g/day would increase IQ by 1.3 points.

The solution is to eat high omega-3 fish with low mercury. The best fish to eat are: salmon, herring, sardines, pollock, and mackerel.

Here’s a nifty fish chart from Expecting Better:

The worst fish to absolutely AVOID are: orange roughy, canned tuna, king mackerel, grouper, shark, swordfish. These contain low omega-3 but have high mercury.

The fish you should avoid for reasons of high mercury are: swordfish, shark, sushi-grade tuna, halibut, tilefish. Even though these contain more omega-3s than the fish in the last list, they contain more mercury than they’re worth.

Finally, these fish are somewhere in the middle: tilefish, halibut, sushi-grade tuna, flounder snapper, catfish, cod. They have acceptable levels of omega-3 and mercury, but there are better fish out there to focus on, like salmon and sardines.

Expecting Better Fish Chart: Fish to Eat When Pregnant

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Like what you just read? Read the rest of the world's best summary of "Expecting Better" at Shortform . Learn the book's critical concepts in 20 minutes or less .

Here's what you'll find in our full Expecting Better summary :

  • Why much parenting advice you hear is confusing or nonsense
  • The most reliable way to conceive successfully
  • How much alcohol research shows you can drink safely while pregnant (it's more than zero)
  • The best foods to eat, and what foods you really should avoid

Allen Cheng

Allen Cheng is the founder of Shortform. He has a passion for non-fiction books (having read 200+ and counting) and is on a mission to make the world's best ideas more accessible to everyone. He reads broadly, covering a wide range of subjects including finance, management, health, and society. Allen graduated from Harvard University summa cum laude and attended medical training at the MD/PhD program at Harvard and MIT. Before Shortform, he co-founded PrepScholar, an online education company.

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