Most tuna is safe during pregnancy, but the type matters. Canned light tuna (skipjack) is one of the lowest-mercury options available and falls in the FDA’s “Best Choices” category, meaning you can eat two to three servings per week. Albacore (white) tuna carries more mercury and should be limited to one serving per week. Bigeye tuna should be avoided entirely.
Why Mercury Matters During Pregnancy
Mercury in fish exists as methylmercury, a form that crosses the placenta easily. Studies have found that infants can end up with higher concentrations of methylmercury in their blood than their mothers, meaning the developing baby absorbs it efficiently. Once it reaches a developing brain, methylmercury interferes with how nerve cells divide, migrate, and connect. It can prevent neurons from multiplying normally and disrupt the signaling pathways that guide brain formation.
At the high exposure levels documented in historical poisoning events, this led to severe neurological damage. The concern during pregnancy isn’t about those extreme scenarios. It’s about chronic low-level exposure from regular fish consumption adding up over months, potentially affecting cognitive development in subtle ways that are hard to detect but worth preventing.
Which Types of Tuna Are Safe
Tuna species vary dramatically in mercury content because bigger, longer-lived fish accumulate more mercury over their lifetimes. Here’s how the FDA categorizes them:
- Canned light tuna (skipjack): Mercury levels below 0.22 parts per million. This is a “Best Choices” fish, safe for two to three 4-ounce servings per week.
- Albacore (white) tuna and yellowfin tuna: Mercury levels ranging from 0.22 to 0.95 parts per million. These fall under “Good Choices,” meaning you should limit yourself to one 4-ounce serving per week.
- Bigeye tuna: Mercury levels high enough to land on the “Choices to Avoid” list. Skip this one entirely during pregnancy. Bigeye is commonly used in sushi-grade tuna steaks and high-end sashimi.
If you’re standing in the grocery aisle looking at cans, the distinction is simple. A can labeled “light tuna” is almost always skipjack. A can labeled “white tuna” or “albacore” is the higher-mercury option. Both are safe in the right amounts, but you can eat roughly three times as much light tuna.
How Much Tuna to Eat Per Week
The FDA and the American College of Obstetricians and Gynecologists both recommend eating 8 to 12 ounces of low-mercury seafood per week during pregnancy, which works out to two or three 4-ounce servings. That recommendation applies to the “Best Choices” category, where canned light tuna sits. If you’re choosing albacore instead, stick to one 4-ounce serving per week and fill the rest of your seafood quota with lower-mercury options.
These aren’t arbitrary limits. Fish provides nutrients that actively support fetal brain development, including omega-3 fatty acids (DHA and EPA), iron, iodine, and choline. Eating too little seafood during pregnancy means missing out on those benefits. The goal is to hit the sweet spot: enough fish for the nutritional payoff, not so much high-mercury fish that it becomes a risk.
Raw Tuna Is Off the Table
Mercury isn’t the only concern with tuna during pregnancy. Raw tuna, including sushi, sashimi, poke bowls, and ceviche, carries the risk of bacterial and parasitic infections. Listeria is the most serious threat because it can cross the placenta and cause miscarriage, stillbirth, or severe illness in newborns. Pregnant people are significantly more susceptible to Listeria infection than the general population.
All seafood during pregnancy should be cooked to 145°F (63°C). That means tuna steaks cooked through, not seared rare. Refrigerated smoked tuna is also risky unless it’s heated in a cooked dish to 165°F. Canned tuna is already fully cooked during the canning process, so it’s safe without any additional preparation.
Other Low-Mercury Fish Worth Eating
Variety matters. The FDA specifically recommends eating a range of seafood rather than the same fish repeatedly, because different species provide different nutrient profiles and spreading your intake across multiple types naturally limits mercury from any single source. Salmon, sardines, anchovies, herring, and shrimp all fall in the “Best Choices” category alongside canned light tuna. Salmon and sardines are particularly rich in DHA, the omega-3 fat most directly linked to fetal brain development.
If you don’t love fish, even two servings a week of any low-mercury option gets you within the recommended range. Canned light tuna is one of the most affordable and accessible ways to get there, which is precisely why it’s worth knowing it’s safe.