What are the risks of consuming raw or undercooked seafood during pregnancy?

Risk of Eating Raw Seafood in Pregnancy

Pregnant women should completely avoid consuming raw or undercooked seafood, including raw shellfish such as oysters, clams, and mussels, due to serious risks of bacterial infection, parasitic disease, and potential harm to both mother and fetus. 1, 2

Primary Infectious Risks

Bacterial Pathogens

• Raw shellfish carries significant risk of Vibrio vulnificus infection, which can cause severe septicemia with mortality rates exceeding 50% in high-risk individuals 3, 4
• Listeria monocytogenes infection occurs 13-17 times more frequently in pregnant women compared to the general population, with devastating consequences including 20% risk of spontaneous abortion or stillbirth 1
• Two-thirds of infants born to mothers with listeriosis develop neonatal infection, including pneumonia, sepsis, or meningitis 1
• Raw seafood also poses risk of Salmonella, Campylobacter, and E. coli infections 1, 3

Parasitic Infections

• Raw oysters and clams can harbor Toxoplasma gondii, which is associated with miscarriage and fetal transmission 1, 2
• Cryptosporidium can survive in oysters for over 1 month despite depuration processes and causes persistent watery diarrhea, particularly dangerous during pregnancy 3

Specific High-Risk Seafood to Avoid

• Raw shellfish (oysters, clams, mussels) present the highest risk and must be completely avoided 1, 2, 4
• Undercooked seafood of any type should not be consumed 1, 2
• Raw fish preparations (such as sushi with raw fish, ceviche, or poke) carry similar infectious risks 1

Why Pregnancy Creates Heightened Vulnerability

• Pregnancy-induced elevation of progesterone causes down-regulation of cell-mediated immune function, increasing susceptibility to intracellular pathogens commonly found in raw seafood 5
• Many foodborne pathogens (Listeria, Toxoplasma, Vibrio) have a predilection for the maternal-fetal unit and can induce death or grave disease in the fetus and newborn 5
• Between 17-33% of all invasive Listeria disease occurs among pregnant women, unborn fetuses, or newborn infants 1

Safe Seafood Consumption Guidelines

• Pregnant women should consume only fully cooked seafood where internal temperature reaches at least 145°F (63°C) for fish 1
• Two servings of cooked fish per week (2 × 140g) are recommended, with one serving from oily fish for omega-3 fatty acids 1
• Avoid high-mercury fish (shark, swordfish, king mackerel, tilefish) even when cooked 6
• Cooked shrimp, crab, and other shellfish are safe when properly prepared 1

Common Pitfalls to Avoid

• Confusion from mixed messaging: While fish consumption is encouraged for fetal neurodevelopment, this applies only to properly cooked fish—never raw or undercooked 7, 8
• Restaurant dining: When eating out, pregnant women must explicitly request that all seafood be cooked until well-done and avoid any raw preparations 2
• Cross-contamination: Raw seafood should never contact other foods, and hands/surfaces must be thoroughly washed after handling 1
• Seaweed products: While generally safe when cooked (as in sushi with cooked fish), some seaweed can contain excessive iodine levels; Nori used in sushi is typically safe 1

Clinical Bottom Line

The risks of raw seafood consumption during pregnancy far outweigh any perceived benefits. 1, 2 The combination of pregnancy-related immunosuppression, the severity of potential infections (Listeria, Vibrio, Toxoplasma), and the catastrophic fetal outcomes (miscarriage, stillbirth, neonatal sepsis, congenital infection) make complete avoidance of raw and undercooked seafood a non-negotiable recommendation. 1, 5 Pregnant women can safely obtain the nutritional benefits of seafood through consumption of properly cooked fish and shellfish. 1, 7