Is tuna safe during pregnancy? With caution — two to three small cans a week
Medically reviewed by Zeinab Alkashaf · August 11, 2026
Quick answer
With caution — canned tuna is permitted during pregnancy within a reasonable limit: two to three small cans a week at most. The reason is mercury, a metal that accumulates in large predatory fish and affects the developing nervous system at high exposure. But note that the message is not "avoid fish": tuna is an excellent source of protein, and fish generally contain omega-3 important for the baby's brain development, and are recommended rather than cut out. The important distinction many women miss: fresh tuna or tuna steak contains more mercury than ordinary canned tuna, and its weekly limit is lower.
Canned and fresh are not the same
This point surprises many women because logic says fresh is always better — true in many things, but not here. Ordinary canned tuna is usually made from smaller, shorter-lived species, so less mercury accumulates in it. Tuna steak and fresh tuna typically come from larger, older fish, and carry a higher concentration.
Ordinary canned tuna: two to three small cans a week at most
Tuna steak or fresh tuna: less than that — consult your doctor; the general rule is to reduce clearly
Smoked or raw tuna (as in sushi): avoided, and here the reason is not mercury but the risk of listeria and parasites
High-mercury fish such as shark, swordfish, and king mackerel: avoided entirely in pregnancy
What to eat instead
The goal is not to eat less fish but to choose the right kinds. Small, oily, low-mercury fish are the ideal choice, combining high omega-3 with low mercury:
Sardines — among the best: cheap, available, and rich in omega-3 and calcium
Salmon — excellent, and cooked thoroughly (not raw or smoked)
Ordinary mackerel (not king mackerel) and fresh herring, well cooked
Tilapia and white fish — low in mercury and easy to digest
Well-cooked prawns and shellfish — with moderate caution, the key being that they are thoroughly cooked
Myth All fish are forbidden in pregnancy because of mercury, so the safest thing is to avoid them entirely.
Fact This is one of the myths where abstaining harms more than it protects. Fish are among the best sources of omega-3 — DHA specifically — important for the baby's brain and retinal development, and two to three servings a week of low-mercury varieties are recommended rather than eliminated. The correct message is selective, not exclusionary: avoid large high-mercury predatory fish, avoid raw and smoked, and eat the rest regularly. The irony is that a woman who avoids all fish out of fear may deprive her baby of an important nutrient in the very act of trying to protect it.
When to ask your doctor
Ask your doctor if you eat tuna or large fish in significant amounts regularly, or if your diet relies heavily on fish. Also ask about omega-3 supplements if you eat no fish at all — whether because you are vegetarian or because the smell is unbearable with nausea — as they may suggest a suitable alternative. And see your doctor if you develop food-poisoning symptoms after eating fish, such as fever, severe vomiting, or diarrhoea, especially with anything resembling flu symptoms, since listeria infection needs prompt assessment in pregnancy.
Frequently asked questions
How many cans of tuna a week are allowed in pregnancy?
Two to three small cans a week at most of ordinary canned tuna. Tuna steak or fresh tuna has a lower limit, because its mercury content is higher.
Is fresh tuna better than canned in pregnancy?
Not where mercury is concerned. Ordinary canned tuna is usually made from smaller, shorter-lived species with less accumulated mercury, whereas tuna steak comes from larger fish with a higher concentration. Limit fresh more than canned.
Which fish are best in pregnancy?
Small, oily, low-mercury fish: sardines, well-cooked salmon, ordinary mackerel, and tilapia. Two to three servings a week are recommended, because omega-3 is important for the baby's brain development.
Dawrat Hayat