Pregnant women can safely eat tuna every week, but how much depends on the type. Canned light tuna (skipjack) is a “Best Choice” fish, meaning you can have 2 to 3 servings per week. Albacore (white) tuna is a “Good Choice,” limited to 1 serving per week. A single serving is 4 ounces, roughly the size of your palm. These categories come from the joint FDA and EPA fish advisory, last revised in October 2021 and still current.
Why the Type of Tuna Matters
Not all tuna is the same when it comes to mercury. The difference comes down to the size and lifespan of the fish: bigger, longer-lived tuna accumulate more mercury in their tissue. Canned light tuna is almost always skipjack, a smaller species with a mean mercury level of about 0.118 parts per million. Albacore, sold as “white” canned tuna or as fresh steaks, averages 0.407 ppm, more than three times higher.
Yellowfin tuna falls into the same “Good Choices” tier as albacore, so limit it to 1 serving per week as well. Bigeye tuna is in an entirely different category: the FDA lists it as a fish to avoid during pregnancy because of its especially high mercury content. Bigeye is common in sushi restaurants, often labeled as “ahi,” so it’s worth asking which species you’re getting.
Fresh Tuna Steaks vs. Canned Tuna
Fresh and frozen tuna steaks tend to carry more mercury than canned versions of the same species. A six-year monitoring study found that fresh tuna averaged 0.517 mg/kg of mercury compared to 0.207 mg/kg in canned tuna. About 11% of the fresh tuna samples tested exceeded permitted mercury limits. Canning often uses smaller fish, and the processing itself can reduce mercury concentrations slightly. If you’re choosing between a tuna steak and a can of chunk light, the canned version is the lower-risk option.
Why Mercury Is a Concern During Pregnancy
Methylmercury, the form of mercury found in fish, crosses the placenta and the blood-brain barrier easily. The developing fetal nervous system is especially sensitive to its effects. At high doses, prenatal mercury exposure is linked to cognitive delays and neurological damage. At lower, chronic levels, the concern is subtler effects on learning, memory, and attention that may not show up until a child is school-aged. This is why the guidelines exist: not to scare you away from fish, but to steer you toward lower-mercury options.
Why You Should Still Eat Fish
Skipping fish entirely during pregnancy has its own drawbacks. Tuna is one of the most accessible sources of DHA, an omega-3 fatty acid that makes up about 15% of the fatty acids in the brain’s gray matter. DHA plays a direct role in how neurons form, how synapses develop, and how signals travel through the brain. Your baby’s brain accumulates DHA throughout pregnancy, but the process accelerates significantly from week 29 through delivery.
The cognitive benefits are measurable and long-lasting. Studies tracking children whose mothers had adequate DHA intake during pregnancy found improved visual acuity in newborns, better coordination in toddlers, and stronger cognitive performance in children tested at ages 5 and 6. These benefits showed up whether the DHA came from fish or from supplements, but the pattern is consistent: adequate omega-3 intake during pregnancy supports brain development in ways that persist for years.
The goal is to eat 2 to 3 servings of lower-mercury fish per week, not to avoid fish altogether. If tuna is what you like and what’s affordable, canned light tuna fits comfortably into that routine.
A Practical Weekly Plan
Keeping track is simpler than it sounds. Each 4-ounce serving is roughly one standard can of tuna (most single-serve cans are around 5 ounces drained, so close enough). Here’s how the math works:
- Canned light tuna (skipjack): Up to 2 to 3 servings per week. You could have a tuna sandwich a few times a week and stay within the guidelines.
- Albacore (white) tuna, canned or fresh: Up to 1 serving per week. If you eat albacore this week, count it toward your total and fill the rest with lower-mercury fish like salmon, shrimp, or cod.
- Yellowfin tuna: Same as albacore, 1 serving per week.
- Bigeye tuna: Avoid entirely during pregnancy.
If you eat a mix of tuna types in the same week, be conservative. One serving of albacore plus one serving of canned light tuna is a reasonable week. The key is variety: rotating between tuna and other low-mercury fish like salmon, sardines, or tilapia lets you get the omega-3 benefits without concentrating your mercury exposure in a single species.
What Counts Toward Your Weekly Limit
Your tuna limit isn’t separate from your overall fish intake. The FDA recommends 2 to 3 total servings of fish per week from the “Best Choices” list, or 1 serving from the “Good Choices” list. If you eat one serving of albacore tuna (a “Good Choice”), that’s your fish for the week under that tier. You can still add servings from the “Best Choices” list, like shrimp or canned light tuna, to reach 2 to 3 total servings.
This applies to all forms of tuna: sandwiches, sushi (as long as it’s cooked or from a reputable source), casseroles, salads. A tuna melt at lunch counts the same as a grilled tuna steak at dinner. If you eat tuna daily, you’ll almost certainly exceed the recommended limits for albacore and could push the boundary even for canned light, so spacing it out across the week is the smarter approach.