Can I Eat Tuna When Pregnant?

Yes, you can eat tuna when pregnant — but there are limits you need to stick to. Tuna is a nutritious fish that provides protein, omega-3 fatty acids, and important minerals. However, it also contains mercury, a naturally occurring heavy metal that accumulates in larger fish. Consuming too much mercury during pregnancy can affect your baby's developing nervous system, which is why the NHS sets specific limits rather than advising you to avoid tuna altogether.

Why Tuna Limits Matter in Pregnancy

Mercury exposure in pregnancy is a concern because methylmercury — the form found in fish — can cross the placenta and pass into breast milk. The developing nervous system of a fetus is particularly sensitive to mercury. The risk is dose-dependent: occasional tuna within the recommended limits is considered safe by the NHS, while regular large amounts would not be.

It is worth noting that canned tuna typically contains lower levels of mercury than fresh or frozen tuna steaks, which is why the limits differ between the two forms. This is because the canning process uses younger, smaller tuna on average, and some mercury is lost during the processing and draining stages.

NHS Guidance on Tuna

• Fresh, frozen, or tinned tuna steaks: no more than 2 portions per week (a portion is around 140g cooked weight)
• Canned tuna: no more than 4 medium-sized tins per week (a tin is around 140g drained weight)

These limits apply in addition to any other oily fish you eat. The NHS recommends eating no more than 2 portions of oily fish per week in total during pregnancy, and tuna counts towards this allowance.

Tuna does not need to be avoided entirely — eating it within these limits is considered safe throughout pregnancy, including the first trimester.

How to Eat Tuna Safely in Pregnancy

• Canned tuna in sandwiches, salads, or pasta is a convenient, affordable option that fits easily within the weekly limit
• Fresh tuna steaks should be cooked thoroughly until the flesh is opaque all the way through — raw or undercooked tuna carries a risk of bacteria and parasites
• Tuna in sushi — sushi-grade raw tuna is generally avoided during pregnancy due to the raw fish risk; if you are eating sushi, choose cooked or vegetable options instead
• Tinned tuna in brine or spring water is a lean protein choice; tinned tuna in oil is also safe but higher in calories

Always check use-by dates, keep tuna refrigerated, and avoid consuming tuna that has been left at room temperature for more than two hours.

If you are tracking your weekly intake, it helps to think of it simply: two tins of canned tuna and one fresh tuna steak in a week would put you at or close to your combined oily fish limit. Vary your fish choices throughout the week — white fish such as cod, haddock, or pollock have no mercury restrictions and are an easy way to keep protein up without worrying about limits.

Other Fish to Be Aware of During Pregnancy

While you're thinking about tuna limits, it is worth knowing the NHS also advises on a small number of other fish during pregnancy due to high mercury content:

• Shark, swordfish, and marlin should be avoided completely during pregnancy — they contain high levels of mercury and there are no safe portions advised
• Oily fish (salmon, mackerel, sardines, trout) are safe and beneficial, but limited to 2 portions per week in total
• White fish (cod, haddock, plaice, coley, hake) and shellfish such as prawns can be eaten freely as long as they are cooked thoroughly — there are no mercury-related restrictions on these

The NHS encourages eating fish during pregnancy rather than avoiding it. Fish provides iodine, DHA (an omega-3 fatty acid), and protein — all of which support your baby's brain and nervous system development. The guidance on tuna is about staying within a sensible limit, not eliminating fish from your diet.

Frequently Asked Questions

If you have eaten slightly over the recommended amount on one occasion, there is no need to panic. The mercury limits are precautionary and based on regular, ongoing consumption — a single instance of eating a little more than advised is unlikely to cause harm. Going forward, stick to the recommended limits and vary the types of fish you eat. If you are worried, speak to your midwife or GP for reassurance.

Is canned tuna safer than fresh tuna in pregnancy?

Canned tuna generally contains lower mercury levels than fresh or frozen tuna steaks, which is why the NHS allows more portions of it per week. Both types are safe within their respective limits. If you are eating both in the same week, keep track so you stay within the combined oily fish allowance of 2 portions per week.

Is tuna safe in the first trimester?

Yes — the same limits apply throughout pregnancy, including the first trimester. There is no period of pregnancy during which tuna needs to be avoided entirely, provided you stick to the NHS guidance on portion limits and cook fresh tuna thoroughly.

This article is for informational purposes only and does not constitute medical advice. Speak to your midwife or GP for advice tailored to your individual pregnancy.

Last reviewed: June 2026

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• Foods to Avoid in Pregnancy
• Pregnancy Vitamins
• Healthy Diet in Pregnancy