Omega 3 in Pregnancy: Which Fish, How Often and Plant Sources
In pregnancy, the type of fish and how often you eat it matter as much as the omega 3 it provides. Oily fish is the omega 3 food to count, shark, swordfish and marlin are the fish to skip, and plant sources help without replacing fish.
At a glance
- Oily fish limit: no more than 2 portions a week in pregnancy, with a portion around 140 g, according to the NHS.
- Fish to skip: shark, swordfish and marlin, which can contain more mercury.
- Tuna: does not count as oily fish, and has its own weekly limit.
- Plant omega 3: walnuts, flaxseed and chia, which the body converts only to a limited extent.
- Rule of thumb: oily fish is the omega 3 food to count, and shark, swordfish and marlin are the fish to skip.
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Which fish count as oily, and how many portions fit a week?
The NHS advice for pregnant women, and for women trying for a baby, is no more than 2 portions of oily fish a week. A portion is around 140 g. Salmon, mackerel, herring and sardines are the usual oily choices, and Harvard’s Nutrition Source lists them among the richest sources of EPA and DHA, the two omega 3 forms found in fish.
Tuna is a special case. The NHS fish page says fresh and canned tuna do not count as oily fish, and tuna has its own weekly limit in pregnancy. Local advice can differ, so ask your midwife which tuna limit applies.
- Write down each fish meal for the week, with the fish type.
- Count each oily fish meal as one portion, using a portion of about 140 g as the guide.
- Stop oily fish once you reach two portions for the week.
- Count tuna on its own line, and check its limit before eating it again that week.
Which fish should pregnant women skip?
Shark, swordfish and marlin should be avoided in pregnancy and when trying for a baby, the NHS says. These fish can contain more mercury than other types, and mercury is the concern because it might harm a developing baby. The NHS also advises avoiding raw shellfish, since that lowers the risk of food poisoning.
How do flaxseed and walnuts fit in?
Walnuts, flaxseed and chia contain ALA, a plant omega 3. Harvard’s Nutrition Source says the body can convert ALA into EPA and DHA, but the conversion rate is limited, and researchers are still uncertain whether ALA alone can provide optimal intakes. That makes these foods useful additions to a desi kitchen, but not a direct swap for fish.
Harvard’s Nutrition Source also says a developing child needs a steady supply of DHA from the third trimester until the second year of life. That is one reason the fish choice matters during pregnancy, and why plant sources are an addition to fish rather than a replacement.
The question for the midwife
Ask which fish the hospital serves, which local fish are safe to eat, and how many oily fish portions fit your week. Local advice can differ from the national page, so the midwife’s answer is the one to follow for your pregnancy.
What should you check on a fish oil product?
Start with the label. Look for where the oil comes from, whether the pack says the oil is tested for contaminants, and where the product is made. Those are the maker’s claims, and a label or a shop claim does not mean a product is approved for use in pregnancy. Ask the midwife or GP before taking any fish oil product, and do not treat one as a way around the fish limits above.
Pregnant women and anyone trying for a baby should keep oily fish to two portions a week and avoid shark, swordfish and marlin. Check any fish oil product with the midwife or GP first. See your midwife the same day if you have fever, vomiting or diarrhoea after eating raw shellfish or raw fish, and do not wait for the symptoms to pass.
Omega 3 and fish questions in pregnancy
Which fish gives omega 3 in pregnancy?
Oily fish such as salmon, mackerel, herring and sardines are the omega 3 choices, with a limit of two portions a week in pregnancy, according to the NHS. Each portion is around 140 g, and tuna is handled separately because it does not count as oily fish.
Is fish oil safe in pregnancy?
Ask the midwife or GP before taking any fish oil product. Products differ, and no pack claim shows that a product is approved for use in pregnancy, so the advice is personal to you.
Which fish should be avoided during pregnancy?
Shark, swordfish and marlin should be avoided, according to the NHS, because they can contain more mercury than other fish. Raw shellfish is also avoided, to lower the risk of food poisoning.
Is tuna safe to eat in pregnancy?
Tuna is allowed within its own weekly limit, and it does not count as oily fish. Check the limit before eating it often, and ask the midwife which tuna figure applies locally.
Can flaxseed replace fish in pregnancy?
Not directly. Harvard’s Nutrition Source says the body converts plant omega 3 into EPA and DHA only to a limited extent, so flaxseed and walnuts add to the diet rather than swap for fish.
Does a developing baby need DHA?
Harvard’s Nutrition Source says a developing child needs a steady supply of DHA from the third trimester until the second year of life. Cold-water oily fish is the main source of EPA and DHA, which is one reason the fish choice in pregnancy matters.
Is omega 3 possible for vegetarian pregnant women?
Plant sources such as walnuts, flaxseed and chia give ALA, but the body converts it to EPA and DHA only to a limited extent. Ask a midwife or dietitian how to cover that gap before deciding anything else.
What should a pregnant woman ask the midwife about fish?
Ask which fish the hospital serves, which local fish are safe to eat, and how many oily fish portions fit the week. Local advice can differ from national pages, so the midwife’s answer counts for your pregnancy.
What if raw shellfish was eaten by accident in pregnancy?
Tell the midwife the same day if fever, vomiting or diarrhoea follows raw shellfish or raw fish. Food poisoning in pregnancy needs prompt advice, so do not wait to see whether symptoms pass.
Related food guides include the foods to avoid list, the pregnancy meal chart, and the fresh fish check for buying. The wider picture of needs across life is in the vitamins by age map. This article sits in our Vitamins and Minerals and Desi Remedies sections.