Pregnant women can safely eat 2 to 3 servings of low-mercury seafood per week, with each serving being about 4 ounces (the size of your palm). That works out to 8 to 12 ounces total per week. The key is choosing the right types of fish, because not all seafood carries the same mercury risk.
The Weekly Limit by Fish Type
The FDA divides fish into three categories based on mercury levels, and each category comes with a different weekly allowance.
“Best Choices” fish are the lowest in mercury, and you can eat 2 to 3 servings per week from this group. These include shrimp, salmon, tilapia, cod, catfish, canned light tuna, sardines, pollock, crab, scallops, clams, oysters, lobster, herring, anchovies, flounder, sole, haddock, squid, trout, and crawfish. This is a long list, so most of the seafood you’d find at a grocery store falls into this category.
“Good Choices” fish have moderate mercury levels. You can eat 1 serving per week from this group, and you shouldn’t eat any other fish that same week. This category includes albacore (white) tuna, yellowfin tuna, halibut, mahi mahi, snapper, grouper, Chilean sea bass, monkfish, and bluefish.
Seven types of fish should be avoided entirely during pregnancy because their mercury levels are consistently high: shark, swordfish, king mackerel, marlin, orange roughy, bigeye tuna, and Gulf of Mexico tilefish.
The Tuna Question
Tuna is one of the most confusing items because different types land in different categories. Canned light tuna (usually skipjack) is a “Best Choice,” meaning 2 to 3 servings per week is fine. Albacore tuna, often labeled “white tuna,” contains roughly three times more mercury than canned light. It falls in the “Good Choices” category, so limit it to one serving per week with no other fish that week. Bigeye tuna, sometimes found at sushi restaurants, is on the avoid list entirely.
Why Seafood Matters During Pregnancy
Eating seafood during pregnancy isn’t just safe within these limits. It’s actively beneficial. Fish is one of the best natural sources of omega-3 fatty acids, particularly DHA, which plays a direct role in your baby’s brain and eye development. Cohort studies have linked higher prenatal seafood intake with improved cognition scores in infants, and one large study found that low seafood intake during pregnancy was associated with lower verbal IQ in children at age 8. Clinical trials have also shown that prenatal DHA consumption improved infant vision and attention span.
The Dietary Guidelines for Americans recommend at least two servings of seafood per week during pregnancy specifically to support these developmental benefits. Many pregnant women actually eat less fish than recommended because they’re worried about mercury, which can backfire by depriving the baby of nutrients that support brain development.
What Mercury Does to a Developing Baby
The reason mercury matters so much during pregnancy is that it crosses the placenta and targets the developing nervous system. In the fetus, mercury interferes with how nerve cells grow, migrate, and connect. It disrupts the structural scaffolding inside nerve fibers, alters signaling between developing brain cells, and can prevent nerve cells from progressing through their normal growth cycle. It also damages the antioxidant systems that protect a newborn’s metabolism.
These effects are why the guidelines exist. The good news is that sticking to low-mercury fish at the recommended amounts keeps exposure well below concerning levels. Researchers have not pinpointed an exact threshold where harm begins, which is precisely why the guidelines build in a wide safety margin.
Raw Seafood Is Off the Table
All seafood during pregnancy needs to be fully cooked. Raw fish, including sushi made with raw fish, can carry parasites and bacteria like Listeria, which is particularly dangerous during pregnancy. Listeria can cross the placenta and cause serious complications even when the mother’s symptoms are mild.
Cook fish to an internal temperature of 145°F. If you don’t have a thermometer, cook it until the flesh is opaque and flakes easily with a fork. Shrimp and lobster should turn opaque white, and clams, mussels, and oysters should open their shells during cooking. Toss any that stay closed. Refrigerated smoked seafood (like lox or smoked trout) is also risky for Listeria unless it’s been heated in a cooked dish to 165°F.
Locally Caught Fish
If you or someone in your family catches fish from local lakes, rivers, or coastal waters, check your state or local fish advisories before eating it. These advisories account for mercury, PCBs, and other contaminants specific to local waterways. If no advisory is available for the body of water where the fish was caught, limit your intake to 6 ounces per week and don’t eat any other fish that week.
If You Don’t Eat Fish
Omega-3 supplements made from fish oil or algae oil can fill the gap if you don’t eat seafood. Algae oil is a solid vegetarian alternative since algae is where fish get their omega-3s in the first place. If you go with algae oil, check the label carefully: some products provide plenty of DHA but are low in EPA, the other important omega-3. You want a supplement that supplies meaningful amounts of both.
That said, whole fish provides a package of nutrients beyond just omega-3s, including protein, selenium, vitamin D, and iodine, that supplements don’t fully replicate. If you can tolerate fish, eating it is the more complete option.