Food for Thought – eating fish in Pregnancy
Trying to follow the guidelines for eating fish in pregnancy can be complicated – there is so much advice out there and it is all different! If you are trying for a baby, pregnant or breastfeeding, read on to help you decide which delicious dish to have for dinner! If you are a Birth Team patient, your private midwife and obstetrician will go through food safety with you at your booking appointment.
What fish is is safe eat in pregnancy?
It’s usually safe to eat sushi and other dishes made with raw fish when you’re pregnant, but with some fish you need to make sure that it’s been frozen first.
You should also limit the amount of some types of fish that you eat while pregnant, such as tuna and oily fish.
Sushi made with raw fish
Occasionally, raw fish like salmon contains small parasitic worms that can make you ill. These worms can cause health problems in people if they eat raw or undercooked fish infected with them.
Infection with these worms can give you abdominal pain, vomiting and diarrhoea.
The disease is very unpleasant, and in very rare cases can be fatal. Eating contaminated fish can also cause allergic reaction. Freezing raw wild fish kills any worms that may be present and makes it safe to eat.
Some farmed fish eaten raw in dishes like sushi, i.e. farmed salmon, don’t need to be frozen beforehand; because of the rearing methods used, these types of farmed fish are very unlikely to contain parasitic worms.
Sushi made with cured fish
Some fish used to make sushi, such as smoked salmon, doesn’t need to be frozen before it’s used because most smoking processes kill any parasitic worms in the fish. Other methods, such as salting or pickling, also make raw fish safe to eat.
Sushi made with shellfish
A lot of sushi contains shellfish, such as shrimp, prawn, crab or scallop; when you’re pregnant, you should only eat cooked shellfish. Raw shellfish can contain harmful viruses and bacteria that can cause food poisoning
If you eat sushi prepared in a restaurant, ask if the shellfish in it has been cooked.
Sushi from shops and restaurants
Lots of the sushi sold in shops isn’t made at the shop. This type of sushi should be fine to eat because if a shop or restaurant buys in ready-made sushi, the raw fish used to make it will have undergone an appropriate freezing treatment.
If you make your own sushi at home, freeze the fish for at least 4 days before using it.
Shellfish includes oysters, crab, prawns, shrimp, mussels, scallops, squid and langoustine. They are low in fat and a source of selenium, zinc, iodine and copper. Some shellfish, such as mussels, oysters, squid and crab, are also good sources of long-chain omega-3 fatty acids, but they do not contain as much as oily fish.
Avoid raw shellfish. It’s advisable not to eat raw shellfish while you’re pregnant to reduce the risk of food poisoning which can be particularly unpleasant in pregnancy: your immune system is suppressed which makes it harder for you to overcome infection. Oysters, mussels, scallops, clams, winkles, prawns, shrimp, crab, crayfish and lobster should not be eaten raw in pregnancy as they can contain harmful bacteria, viruses or toxins that can make you ill.
It’s safe to eat shellfish during pregnancy as long as it’s been thoroughly cooked. Any bacteria or viruses are usually killed by thorough cooking. However, if toxins are present, they will not be completely removed by cooking.
How much shellfish should I eat?
Although it is recommended that regular fish-eaters should avoid eating brown crab meat too often, there is no need to limit the amount of white crab meat that you eat. There are no maximum recommended amounts for other types of shellfish.
How much fish should you eat in pregnancy?
A healthy diet should include at least two portions of fish a week, including one of oily fish.
Fish and shellfish are good sources of important vitamins and minerals. Oily fish – such as salmon and fresh tuna – is also high in long-chain omega-3 fatty acids, which may help to keep your heart healthy.
Although most of us should have more fish in our diet, including more oily fish, there are maximum recommended amounts for oily fish, crab and some types of white fish. There is additional advice for women who are pregnant or breastfeeding.
Fish that is steamed, baked or grilled is a healthier choice than fried fish.
Different types of fish and shellfish provide different nutrients.
Sardines, anchovies, carp, herring, mackerel, pilchards, salmon, whitebait, fresh tuna and trout are all examples of oily fish, meaning they are good sources of long-chain omega-3:
Tinned tuna does not count as oily fish. Fresh tuna is an oily fish, but when it is canned the amount of long-chain omega-3 fatty acids is reduced to levels similar to those in other white fish.
Some oily fish contains bones that you can eat. These include whitebait, canned sardines, pilchards and tinned salmon (but not fresh salmon). These fish are good sources of calcium and phosphorus, which help keeper bones strong.
Oily fish and omega-3 fatty acids
Oily fish contains a special kind of fat, called long-chain omega-3 fatty acids.
Long-chain omega-3 may help to prevent heart disease. It is also important for women who are pregnant or breastfeeding, because it can help a baby’s nervous system to develop.
Oily fish are the richest source of long-chain omega-3. Some white fish and shellfish also contain long-chain omega-3, but not as much as oily fish.
The main shellfish sources of long-chain omega-3 are mussels, oysters, squid and crab.
How much oily fish should I eat?
We should eat at least one portion (around 140g when cooked) of oily fish a week.
Oily fish can contain low levels of pollutants that can build up in the body. Women who are planning a pregnancy or who are currently pregnant or breastfeeding should eat no more than two portions of oily fish a week. This is because pollutants found in oily fish may affect the future development of a baby in the womb. Pregnant women and women who are trying to get pregnant should not eat swordfish, as it contains more mercury than other fish.
Cod, haddock, plaice, pollock, coley, dab, flounder, red mullet, gurnard and tilapia are all examples of white fish.
White fish are low in fat, making them one of the healthier, low-fat alternatives to red or processed meat, which tends to be higher in fat, especially saturated fat, and a source of omega-3 fatty acids, but at much lower levels than oily fish
How much white fish should I eat?
You can safely eat as many portions of white fish per week as you like, except for sea bream, sea bass, turbot, halibut and rock salmon which can contain similar levels of certain pollutants as oily fish; anyone who regularly eats a lot of fish should avoid eating these five fish too often.
Even though shark and marlin are white fish, there is separate advice about how much of them you should eat: pregnant women and women who are trying to get pregnant should not eat shark or marlin as they contain more mercury than other fish.
Advice from the Scientific Advisory Committee on Nutrition and the Committee on Toxicity about eating fish when trying to get pregnant, or when pregnant or breastfeeding:
- Shark, swordfish and marlin: do not eat these if you are pregnant or trying to get pregnant. All other adults, including breastfeeding women, should eat no more than one portion per week. This is because these fish can contain more mercury than other types of fish, and can damage a developing baby’s nervous system.
- Oily fish: if you are trying for a baby, or are pregnant or breastfeeding, you should have no more than two portions of oily fish a week. A portion is around 140g.
- Canned tuna: if you are trying for a baby or are pregnant, you should have no more than four cans of tuna a week. This is because tuna contains higher levels of mercury than other fish. If you are breastfeeding, there is no limit on how much canned tuna you can eat.
These figures are based on a medium-sized can of tuna with a drained weight of around 140g per can.
Remember, canned tuna doesn’t count as oily fish. So if you’ve had a portion of canned tuna during the week, you can still have up to two portions of oily fish.
Due to the higher levels of mercury in tuna, if you’re eating canned tuna, don’t pick fresh tuna as your oily fish.
Unless you are advised otherwise, avoid taking fish liver oil supplements when you’re pregnant or trying for a baby. These are high in vitamin A (retinol), which can be harmful to your unborn baby. Pregnant women are advised to avoid taking supplements that contain vitamin A.