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Is it safe? · Pregnancy Smart

Are oysters safe during pregnancy?

Assigned clinical reviewerMichael Yuzefovich· MD, FACOGDraft · pending clinical reviewUpdated

What does the evidence say about oysters during pregnancy?

  1. Vibrio infection usually comes from eating raw or undercooked shellfish, and in pregnancy the main worries are the high fever it can cause and the dehydration from vomiting and diarrhea. 1
  2. Raw oysters, mussels, and clams can carry the Toxoplasma parasite, and cooking them fully is the safer choice during pregnancy. 2
  3. Oysters are the shellfish most often linked to norovirus outbreaks, since they can selectively pull norovirus particles from the water as they filter feed. 3
  4. A 2022 outbreak traced to oysters harvested from Galveston Bay, Texas shows commercially harvested oysters can still cause norovirus illness, not just informally caught ones. 4
  5. Fully cooked oysters are also one of the richest food sources of zinc, a mineral you need more of in pregnancy, about 11 mg a day. 5

Is oysters safe in each trimester?

  • First trimester. Skip raw and undercooked oysters for now. A fever from a Vibrio infection has been linked to a small rise in certain birth defects when it happens early in pregnancy, so fully cooked shellfish matters most this trimester.
  • Second trimester. The same raw-oyster caution continues. Fully cooked oysters are a great source of zinc too, a mineral you need about 11 mg of daily during pregnancy.
  • Third trimester. This is the trimester to be most careful about dehydration, since vomiting and diarrhea from a foodborne infection have been tied to low amniotic fluid and preterm labor. Keep choosing oysters cooked all the way through, and call your provider promptly for fever or if you can't keep fluids down.

Frequently asked questions

Can I eat oysters if they're fully cooked during pregnancy?

Yes. Oysters cooked until the flesh is opaque and firm all the way through, roughly an internal temperature of 145°F, are a lower-risk choice and a concentrated source of zinc. The caution here is specifically about raw or undercooked oysters, including many raw-bar and half-shell preparations.

Are char-grilled oysters at a restaurant safe to eat while pregnant?

Char-grilled oysters can be a reasonable choice, but only if each oyster is cooked all the way through rather than briefly seared with the center still raw, which does happen at some raw bars. If you are unsure how thoroughly they were cooked, it is fine to ask your server or choose a fully baked or steamed preparation instead.

How do I know an oyster is cooked enough to eat during pregnancy?

Look for flesh that is opaque, firm, and plump rather than translucent or shrunken, reaching roughly 145°F inside. Many seafood-safety guides also suggest skipping any in-shell oyster that stays tightly closed after cooking, since that can mean it was not viable before it went on the heat. When in doubt, choose a different piece.

What are the signs of a Vibrio or norovirus infection from oysters, and when should I call my provider?

Watery diarrhea, stomach cramping, nausea, vomiting, and sometimes fever are typical, usually starting within a day or two of eating raw or undercooked shellfish. Call your obstetric provider promptly for a fever, an inability to keep fluids down, or other signs of dehydration, since both fever and dehydration carry their own pregnancy-specific concerns.

Related in the library

References

  1. Vibrio: MotherToBaby Fact Sheet

    MotherToBaby · https://mothertobaby.org/fact-sheets/vibrio-pregnancy/

  2. About Toxoplasmosis

    CDC · https://www.cdc.gov/toxoplasmosis/about/index.html

  3. Oysters and norovirus: something special?

    PubMed · https://pubmed.ncbi.nlm.nih.gov/31910598/

  5. Zinc: Fact Sheet for Consumers

    NIH · https://ods.od.nih.gov/factsheets/Zinc-Consumer/

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.