You actually can eat fish while pregnant, and health agencies recommend that you do. The real guidance is more nuanced than a blanket ban: certain fish carry too much mercury, raw or undercooked fish poses infection risks, and some smoked varieties harbor dangerous bacteria. But well-chosen, properly cooked fish is one of the best foods you can eat during pregnancy because of its benefits for your baby’s brain development.
Mercury Is the Main Concern
The primary reason some fish are off-limits during pregnancy is mercury, specifically a form called methylmercury that accumulates in fish as they eat smaller organisms. Large, long-lived predator fish concentrate the most mercury in their flesh because they spend years absorbing it from everything they eat.
Methylmercury is uniquely dangerous during pregnancy because it mimics an amino acid your body uses naturally, allowing it to slip across the placenta and through your baby’s developing blood-brain barrier. Once inside, it disrupts the normal sequence of brain cell development, causing neurons to form too early and skip critical intermediate stages. This can interfere with how your baby’s brain wires itself during the months when that process is most active.
The FDA and EPA say pregnant and breastfeeding women should completely avoid these seven fish:
- King mackerel
- Marlin
- Orange roughy
- Shark
- Swordfish
- Tilefish (from the Gulf of Mexico)
- Bigeye tuna
These species sit at the top of the food chain or live for decades, giving mercury more time and opportunity to build up in their tissue.
The Canned Tuna Question
Canned tuna is where many pregnant women get confused, because not all tuna is the same. Canned light tuna (usually skipjack) contains significantly less mercury than canned albacore (white) tuna. Albacore is a larger species that accumulates more mercury over its longer lifespan.
Health Canada sets a specific limit for albacore tuna at 300 grams per week for pregnant women, roughly two standard cans. Light tuna doesn’t carry the same restriction. If tuna is a staple in your diet, switching to light tuna is a simple way to reduce your mercury exposure without giving it up entirely.
Raw Fish and Infection Risk
Mercury aside, raw and undercooked seafood poses a separate problem: foodborne illness. Pregnancy suppresses parts of your immune system, making you more vulnerable to infections that your body might normally fight off easily.
The biggest threat is a bacterium called Listeria, which is unusual because it thrives at refrigerator temperatures where most bacteria can’t grow. A Listeria infection during pregnancy can lead to miscarriage, stillbirth, premature delivery, or serious illness in a newborn. Raw seafood is one of its common hiding places.
This means avoiding sushi, sashimi, raw oysters, raw clams, raw scallops, and ceviche for the duration of your pregnancy. Cooking kills both Listeria and any parasites that might be present in raw fish. Even though “sushi-grade” fish is flash-frozen to kill parasites, freezing does not eliminate Listeria, so U.S. food safety agencies do not consider frozen raw fish safe for pregnant women.
Smoked Fish Has a Hidden Risk
Refrigerated smoked seafood is another Listeria concern that catches people off guard. Products labeled “nova-style,” “lox,” “kippered,” “smoked,” or “jerky” that you find in the refrigerator section or at deli counters are not fully cooked. Because Listeria can grow even under refrigeration, these products carry real risk.
The exception: shelf-stable or canned smoked seafood is safe. The canning process uses high enough heat to kill Listeria. Refrigerated smoked fish is also fine if you cook it into a hot dish, like a casserole or a baked pasta, before eating it. The key distinction is whether the product has been heated to a temperature that destroys bacteria.
How to Cook Fish Safely
All fish and shellfish should reach an internal temperature of 145°F (63°C) to be safe during pregnancy. If you don’t have a food thermometer, look for these signs:
- Finfish: The flesh turns opaque (milky white) and flakes easily with a fork.
- Shrimp and lobster: The flesh turns opaque white.
- Scallops: They become opaque and firm.
- Clams, mussels, and oysters: The shells open during cooking. Discard any that stay closed.
Why You Should Still Eat Fish
The reason health agencies encourage fish consumption during pregnancy, rather than simply warning against it, is omega-3 fatty acids. These fats are critical building blocks for your baby’s brain and eyes, particularly for the insulation that forms around nerve fibers and for visual development in the weeks before and after birth. Some studies have found that omega-3 supplementation during pregnancy improved measures of infant cognitive development by 6% to 11%, though results have been inconsistent across different types of developmental outcomes.
Low-mercury fish that are rich in omega-3s include salmon, sardines, anchovies, herring, and trout. These are small, short-lived species that don’t accumulate much mercury. Eating two to three servings per week of these types of fish gives you the nutritional benefits while keeping mercury exposure well within safe limits.
Locally Caught Fish Needs Extra Caution
Fish from local lakes, rivers, and streams follow different rules than store-bought seafood. Local waterways may be contaminated with mercury or industrial chemicals, and many bodies of water have specific advisories posted by state or regional agencies. If you or someone you know catches fish from local waters, check for advisories before eating it.
When no advisory exists for a particular waterway, the FDA recommends limiting yourself to one serving (no more than 6 ounces) per week and eating no other fish that week. The absence of an advisory doesn’t mean the water has been tested and found safe. It may simply mean no one has tested it yet.