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Best Fish Oil for Pregnancy

Omega-3 fatty acids (DHA and EPA) are important for your baby's brain and eye development. Here's how to choose a safe fish oil.

Getting enough omega-3 during pregnancy is genuinely worthwhile. DHA (docosahexaenoic acid) in particular accumulates in your baby's brain and retina during the second and third trimesters, and many pregnant women in the UK do not get enough from diet alone. Fish oil supplements can help bridge that gap — but not all supplements are equally suitable during pregnancy, and there are important distinctions to understand before you buy.

Table of Contents

  1. What to Look For
  2. Benefits of Omega-3 in Pregnancy
  3. What to Avoid
  4. Getting Omega-3 From Food
  5. FAQ

What to Look For

When choosing a fish oil supplement during pregnancy, look for these features:
  • High DHA content. DHA is the omega-3 most relevant to brain and eye development. Look for a supplement that clearly states how much DHA it contains per capsule, not just the total fish oil amount.
  • Purified or molecularly distilled. This process removes contaminants including mercury, PCBs, and dioxins, which accumulate in fish fat. Quality pregnancy supplements should carry a statement about purification.
  • Third-party tested. Independent testing (for example by organisations such as IFOS — the International Fish Oil Standards Programme) provides additional confidence that a supplement contains what it says and is free from contaminants.
  • From small, oily fish. Fish oil derived from smaller species such as sardines, anchovies, and mackerel tends to carry fewer contaminants than oil derived from larger predatory fish.
  • No added vitamin A. This is critical — see the section below.

Benefits of Omega-3 in Pregnancy

The NHS recommends eating two portions of fish per week during pregnancy, including one portion of oily fish. Oily fish — such as salmon, mackerel, sardines, and trout — are the richest dietary source of DHA and EPA. For those who do not eat oily fish regularly, a supplement provides an alternative route.

Evidence supports a role for omega-3 in:

  • Brain development — DHA is a structural component of brain tissue and accumulates rapidly in the third trimester.
  • Eye development — DHA is also found in high concentrations in the retina.
  • Supporting a healthy pregnancy. There is reasonable evidence that adequate omega-3 intake is associated with healthy outcomes, though individual circumstances vary.

Omega-3 supplementation is generally considered beneficial and safe during pregnancy, but it is not a substitute for a varied, balanced diet.

What to Avoid

There is one important supplement to avoid during pregnancy:

Cod liver oil. Unlike standard fish oil, cod liver oil contains high levels of vitamin A (retinol). Excessive vitamin A intake during pregnancy is associated with birth defects. The NHS specifically advises pregnant women not to take cod liver oil supplements. This is a widely misunderstood distinction — cod liver oil and fish oil are not the same product.

Also be cautious of:

  • Supplements with very high doses — more is not always better, and very high doses of omega-3 may have blood-thinning effects. Stick to doses within normal supplementary ranges and discuss any concerns with your midwife.
  • Supplements from large predatory fish such as shark, swordfish, or marlin — these accumulate higher levels of mercury.

Getting Omega-3 From Food

If you prefer to meet your omega-3 needs through food, the NHS recommends up to two portions of oily fish per week during pregnancy. Good sources include:
  • Salmon (fresh, frozen, or tinned)
  • Mackerel (not smoked, which is high in salt)
  • Sardines
  • Trout
  • Herring

Tinned tuna counts towards your two portions of white fish per week but does not count as oily fish for omega-3 purposes.

Algae-based DHA supplements are an excellent vegan and vegetarian alternative. The omega-3 in fish originally comes from algae (fish accumulate it by eating algae and smaller fish), so algae-based supplements go directly to the source. These are suitable for anyone avoiding fish products and are free from the contamination concerns associated with fish-derived oils.

FAQ

### Is fish oil safe in pregnancy?

Yes — high-quality, purified fish oil is considered safe during pregnancy. The key is to choose a supplement that has been processed to remove mercury and other contaminants, and to ensure it does not contain vitamin A. Look for products specifically labelled for use in pregnancy. Algae-based DHA is also safe and suitable for vegans and vegetarians.

Should I take fish oil or just eat oily fish?

Either approach can work. If you regularly eat one to two portions of oily fish per week, you may be meeting your DHA needs through diet. If you do not eat oily fish — whether due to preference, diet, or allergy — a supplement is a practical way to ensure you are getting enough DHA. Discuss your specific situation with your midwife or GP, particularly if you have a fish allergy.

What is the difference between fish oil and cod liver oil?

Fish oil and cod liver oil are both derived from fish but are different products with different nutritional profiles. Standard fish oil is extracted from the flesh of oily fish and is high in omega-3 fatty acids with low vitamin A levels. Cod liver oil is extracted from cod liver and contains high levels of vitamin A (retinol). The NHS advises pregnant women not to take cod liver oil because excessive vitamin A can be harmful to the developing baby. Always read the label carefully.

Always speak to your midwife or GP before starting any new supplement during pregnancy, particularly if you have an existing health condition or take any medication.