Fish is one of the best things you can eat while pregnant, yet it is the food many people quietly drop because the rules feel confusing. Here is exactly what counts as oily, how much tuna is fine, why smoked salmon needs heating, and how to build a week of fish that stays inside the NHS limits.
Last reviewed 7 October 2026 · Checked against NHS guidance · 9 min read
The short answer
Yes, you can eat tuna while pregnant in the UK: no more than 4 medium cans or 2 fresh tuna steaks a week. Keep oily fish such as salmon, mackerel, sardines and trout to 2 portions a week. White fish and cooked shellfish have no weekly limit. Avoid shark, swordfish and marlin, raw fish and raw shellfish. Sushi is fine if the fish is cooked, and smoked salmon is fine once it is cooked until steaming hot.
This is the deep dive on fish. For every other food, from cheese to cured meat, see our complete pregnancy food safety checklist.
Why you should keep eating fish in pregnancy
The limits get the headlines, so it is easy to come away thinking fish is risky. The NHS says the opposite: eating fish is good for your health and for the development of your baby. Its general advice in pregnancy is to try to eat 2 portions of fish a week, 1 of which should be oily.
White fish such as cod, haddock and pollock is low in fat, and shellfish is a source of selenium, zinc, iodine and copper. The goal is not less fish, but the right mix.
Exactly which fish count as oily (and which do not)
Most confusion comes from one fact: tuna is not an oily fish under NHS guidance, fresh or canned. It has its own separate limit. That means a tuna sandwich does not use up one of your 2 oily portions, and a salmon fillet does not count towards your tuna.
Oily fish
Max 2 portions a week in pregnancy
- Salmon
- Tinned salmon
- Trout
- Mackerel
- Sardines
- Pilchards
- Herring
- Kippers
- Sprats
Tuna
Own limit: 4 cans or 2 steaks
- Tinned tuna
- Fresh tuna steak
White fish
No weekly limit when cooked
- Cod
- Haddock
- Pollock
Canned counts too. The NHS lists canned sardines, pilchards and tinned salmon as oily fish, so a sardines-on-toast lunch is one of your 2 portions. Kippers and bloaters are types of herring, so they count as oily as well. The NHS says a portion is around 140g.
Can I eat tuna when pregnant? The limit and the reason
Yes. If you are pregnant or trying for a baby, the NHS says to have no more than 4 cans of tuna a week or no more than 2 tuna steaks a week. Those figures are based on a medium can with a drained weight of around 140g, and a fresh steak of about 140g cooked.
The reason is mercury. The NHS explains that tuna contains higher levels of mercury than other fish. Mercury is the same reason shark, swordfish and marlin are off the menu completely, because in larger amounts it can damage a developing baby's nervous system. The tuna limit lets you keep eating it without having too much.
A few practical points people ask about:
- A tuna sandwich or jacket potato topping usually uses part of a can, not a whole one. If you share a can across two lunches, that is half a can each time.
- Tuna sushi or a seared tuna steak follows two rules: it counts towards the tuna limit, and it must be cooked, not raw.
- Once your baby is born, the NHS says there is no limit on tuna while breastfeeding. The 2-portion oily fish limit still applies while you breastfeed.
Why oily fish is good but still limited
Oily fish is where the omega-3 and vitamin D are, so why cap it? The NHS explains that pollutants found in oily fish may build up in the body and affect the future development of a baby in the womb. Two portions a week gives you the benefits while keeping that build-up low.
This is not only a pregnancy rule. The NHS gives the same 2-portion limit to girls, women who are planning a pregnancy or may have a child one day, and women who are breastfeeding. Because pollutants build up over time, it is worth following before you conceive, not just once you have a positive test.
Shark, swordfish and marlin: avoid completely
These large fish can contain more mercury than other types of fish, and the NHS says that mercury can damage a developing baby's nervous system. Avoid them if you are pregnant or planning a pregnancy.
Fish week checker
Tap in the fish you plan to eat this week. It checks your plan against the NHS pregnancy limits for oily fish and tuna, and the 2-portions-a-week goal.
The NHS gives the tuna limit as 4 cans or 2 steaks. When you mix the two, this checker counts one steak as two cans, which is our reading rather than an NHS figure. For full meal planners and shopping lists, see the Complete Pregnancy Nutrition Course.
Can I eat sushi when pregnant in the UK?
Sometimes. The NHS says sushi made with cooked fish or cooked shellfish is fine. Sushi made with raw fish or raw shellfish is not, and that applies even if the fish has been previously frozen.
Raw fish and raw shellfish can contain bacteria or toxins that can make you seriously unwell or give you food poisoning. Raw fish can also carry listeria, the bacterium behind many pregnancy food rules.
Cooked shellfish and cooked fish are fine in sushi.
No fish, no fish rules.
Raw fish, even if previously frozen.
Cold-smoked salmon in sushi is not cooked until steaming hot.
At a sushi bar or with a supermarket pack, check which items are cooked. If you cannot tell whether the fish has been cooked through, ask, or pick a cooked or vegetable option instead.
Smoked salmon, gravlax and other cured fish
The NHS says cold-smoked and cured fish, like smoked salmon, must be cooked until steaming hot before you eat it in pregnancy. Raw, cold-smoked and cured fish could contain listeria, which causes listeriosis. The NHS fish page puts it simply: in pregnancy, only eat smoked fish products that have been thoroughly cooked.
That rules out cold slices on a bagel or a platter, and cold gravlax. Stirred into hot pasta or scrambled eggs until steaming, or baked into a hot dish, it is fine. Smoked salmon still counts as salmon, so it uses one of your 2 oily portions. The same listeria logic sits behind the soft cheese rules, explained in our guide to cheese in pregnancy.
Prawns, crab, mussels and other shellfish
Cooked shellfish is safe in pregnancy. The NHS lists prawns, crab, lobster, squid, mussels, scallops, clams and cockles as fine when cooked, and there is no weekly limit.
Two catches. First, raw shellfish such as raw oysters should be avoided, because shellfish that is raw or not thoroughly cooked can contain harmful viruses and bacteria. Second, cold, pre-cooked ready-to-eat prawns, the kind in a prawn cocktail or a supermarket sandwich, should be cooked until steaming hot before you eat them.
Cod liver oil and fish liver oil supplements
This is where fish advice and supplement advice cross. The NHS says do not take cod liver oil or any supplement containing vitamin A (retinol) when you are pregnant. Fish liver oil supplements are high in vitamin A, and too much vitamin A can be harmful to an unborn baby. The same reason sits behind the advice to avoid liver and liver pâté.
The NHS pages we checked do not give advice on omega-3 fish oil supplements made from the body of the fish rather than the liver. If you are thinking about one, check the label for vitamin A or retinol and ask your midwife or pharmacist. Our guide to pregnancy vitamins in the UK covers what the NHS does recommend, and the Pregnancy Vitamins and Supplements course includes a supplement label checker.
A week of fish that stays inside the limits
Here is one simple pattern that hits the NHS goal of 2 fish portions with 1 oily, uses some tuna, and stays well inside every limit.
Example week
On Monday, a baked salmon fillet with potatoes and greens: oily portion one. On Wednesday, a tuna and sweetcorn jacket potato using half a can, then the other half in a sandwich on Thursday: one can in total. On Friday, fish pie made with cod, haddock and cooked prawns, heated until steaming: white fish and shellfish, no limit. At the weekend, sardines on toast from a tin: oily portion two.
That is 2 of 2 oily portions and 1 of 4 cans of tuna. What would tip it over: a third oily meal, such as a smoked salmon pasta, or adding two fresh tuna steaks on top of the cans. For a full day of meals built around a fish dinner, see our one-day pregnancy meal plan.
If this kind of planning helps, the Complete Pregnancy Nutrition Course has three ready-made meal planners and shopping lists that already balance fish, iron and vitamin D across the week.
Ate raw sushi or cold smoked salmon before you knew?
The NHS says that if you have already had a small amount of food that should be avoided in pregnancy, it is unlikely to affect your baby if you did not get ill. Call NHS 111 or use 111 online if you are pregnant and:
- you feel unwell after eating food that should be avoided in pregnancy
- you have had vomiting and diarrhoea for more than 48 hours
- you have symptoms of listeriosis
Your midwife can answer questions about your own pregnancy.
Go further than the fish rules
Our courses cover the rest of your plate, with tools that save as you go.
Pregnancy Food Safety
Fish, runny eggs, soft cheese, caffeine and takeaways in depth, with a cheese checker and a caffeine counter.
Complete Pregnancy Nutrition
Three meal planners, a fridge-door safe and avoid list, shopping lists and a supplement tracker.
See all pregnancy courses.
Related guides
- How much caffeine is 200mg?: mugs, cans and bars added up.
- What to eat with morning sickness: food ideas for a queasy day.
- Preconception checklist: what to do before trying, including supplements.
Questions people ask
How many tins of tuna can I eat a week when pregnant?
No more than 4 medium cans a week, based on a drained weight of around 140g per can. If you eat fresh tuna instead, the limit is 2 steaks of about 140g cooked.
Does tuna count as an oily fish?
No. Under NHS guidance, fresh and canned tuna do not count as oily fish. Tuna has its own limit, separate from the 2 portions of oily fish a week.
Can I eat smoked salmon when pregnant?
Only when it is cooked until steaming hot, such as stirred into hot pasta. Cold-smoked and cured fish, including smoked salmon and gravlax, could contain listeria.
Can I eat sushi if the fish was frozen first?
No. The NHS says to avoid sushi made with raw fish even if it has been previously frozen. Sushi made with cooked fish, cooked shellfish or vegetables is fine.
Can I eat prawns when pregnant?
Yes, cooked prawns are fine. Cold, pre-cooked ready-to-eat prawns should be cooked until steaming hot first. Avoid raw prawns and other raw shellfish.
Is salmon safe in pregnancy?
Yes. Cooked salmon, including tinned salmon, is safe and is a good source of omega-3 and vitamin D. It counts as oily fish, so keep to 2 portions of oily fish a week.
Can I take cod liver oil when pregnant?
No. The NHS says do not take cod liver oil or any supplement containing vitamin A (retinol) in pregnancy, because too much vitamin A can harm an unborn baby.
Sources
- NHS: Foods to avoid in pregnancy (page last reviewed 15 June 2026)
- NHS: Fish and shellfish
- NHS: Have a healthy diet in pregnancy
- NHS: Vitamins, supplements and nutrition in pregnancy
This article is general information based on UK public health guidance. It is not medical advice. If you have a health condition, an allergy or questions about your own pregnancy, speak to your midwife, GP or pharmacist.
