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The Importance of Omega-3 During Pregnancy: DHA Benefits, Recommended Intake and Best Sources

Omega-3 fatty acids, particularly DHA, play an important role in supporting your baby’s brain, eye and nervous system development during pregnancy. Oily fish such as salmon, sardines, mackerel and herring are good sources of DHA, while algae-based supplements can provide a plant-based alternative. In the UK, pregnant women are advised to eat fish regularly but limit oily fish to no more than two portions a week and avoid high-mercury fish such as shark, swordfish and marlin.

Omega-3 fatty acids are essential nutrients, meaning your body can’t produce them on its own and they need to come from your diet or via supplementation.¹ During pregnancy, omega-3s play an important role in supporting your baby’s development, especially the brain and eyes.
They’re also linked to aspects of maternal wellbeing, including heart health, inflammation balance, and mood. Despite this, many women in the UK may not be getting enough, particularly if oily fish isn’t a regular part of their diet.
In this article, we’ll explore what omega-3 fatty acids are, why they matter in pregnancy, how much you might need, and the safest ways to include them in your diet, whether you eat fish or follow a plant-based lifestyle.
Want to learn more? Find clear, expert-written information on the physical, emotional and practical aspects of pregnancy.

What are omega-3 fatty acids?

Omega-3 is an umbrella term for a group of fats that are important for human health. There are three main types²:

ALA (alpha-linolenic acid)

Found in plant foods like flaxseeds, chia seeds, and walnuts.
ALA’s main role is to be converted into the other omega-3 forms by the body, though this conversion is limited – only 5-10% to EPA and less than 1% to DHA – meaning it is not a suitable source of omega-3 on its own.³

EPA (eicosapentaenoic acid)

Found in marine sources like fish and algae.
EPA plays a role in supporting inflammation balance, blood clotting and cardiovascular health.

DHA (docosahexaenoic acid)

Found in marine sources like fish and algae.
DHA is the particuarly important omega-3 in pregnancy, as it is a key structural component of the brain and retina. It is important in supporting visual development, cognitive performance, and neurological health.

Why is omega-3 important during pregnancy?

As mentioned above, omega-3 has functions in both cognitive and cardiovascular health, but how does this relate to pregnancy?

How DHA supports your baby’s brain and eye development

One of the most well-established roles of omega-3 in pregnancy relates to your baby’s brain and eyes.
DHA is a major structural component of brain and retinal tissue, meaning it’s used as a building block as your baby grows. During the second half of pregnancy, and especially in the third trimester, your baby’s brain develops rapidly, and DHA is transferred from mother to baby via the placenta to support this process.⁴ As the body isn’t very efficient at producing DHA on its own, your baby relies heavily on your dietary intake, which is why requirements may increase during pregnancy.
Research helps illustrate what this looks like in real life. Large population studies have found that higher maternal seafood intake during pregnancy is associated with improved measures of child development, including communication, motor skills, and behaviour. For example, findings from the well-known ALSPAC study showed that children of mothers who consumed little to no seafood during pregnancy were more likely to have lower scores in areas such as verbal IQ and social development.⁵ Similar patterns have been seen in other populations, where higher fish intake during pregnancy has been linked with small but meaningful improvements in cognitive outcomes.⁶
There is also some emerging research exploring whether omega-3 intake during pregnancy – and in some cases during breastfeeding – may influence aspects of a baby’s health after birth, particularly in relation to immune development. Omega-3s continue to be passed to your baby through breast milk, and some studies suggest a potential link with a lower risk of early childhood allergies.^7,8
Researchers have also begun to explore whether omega-3 may play a role in early infant behaviour, including sleep patterns, although evidence in this area is still developing and not yet consistent, so more research is needed before clear conclusions can be drawn.^9,10,11
Overall, the evidence suggests that omega-3 (particularly DHA) may play an important role in supporting your baby’s development, both during pregnancy and in early life. Discover supplements formulated for use during pregnancy.

Can omega-3 support healthy pregnancy outcomes?

Omega-3 may also influence how pregnancy progresses, particularly in relation to gestational length (how long pregnancy lasts).
From a biological perspective, omega-3 fatty acids are involved in the production of compounds that help regulate inflammation and the timing of labour. This has led researchers to explore whether increasing intake could affect the risk of preterm birth. A review of nearly 20,000 women found that omega-3 supplementation during pregnancy was associated with a reduced risk of preterm birth (before 37 weeks) and early preterm birth (before 34 weeks), and earlier studies found those taking omega-3 supplementation had slightly longer pregnancies on average compared to those who did not^12,13.
While these findings are encouraging, they don’t mean omega-3 prevents preterm birth entirely. Instead, they suggest it may play a supportive role alongside other aspects of maternal health and care.

Omega-3 and maternal wellbeing during pregnancy

Omega-3 fatty acids are also involved in processes that support your own health during pregnancy, not just your baby’s.
EPA and DHA influence inflammation, cardiovascular function, and the way cells communicate, particularly in the brain. Therefore, whether omega-3 intake may be linked to mood during and after pregnancy is an area of growing interest, particularly as emotional wellbeing can fluctuate during this time for many different reasons.
Some observational studies have found that women who consume little or no seafood during pregnancy are more likely to report higher levels of depressive symptoms. Similarly, lower levels of omega-3 in the body have been associated with a greater likelihood of low mood in some research settings^14,15.
However, it’s important to approach these findings with care. Observational studies can show links, but they don’t prove cause and effect. When omega-3 supplements have been tested in clinical trials, results have been mixed.¹⁶ Currently, omega-3 is best viewed as one part of a balanced diet that supports general wellbeing, rather than a specific approach to managing mood or a way to prevent postnatal depression.
If you have any concerns about how you’re feeling during pregnancy or after birth, it’s important to speak to your GP or midwife for support.

Are you getting enough omega-3 during pregnancy?

Despite its importance, many women may not be getting enough omega-3 during pregnancy. Studies suggest that average intakes of oily fish (the main source of DHA and EPA) are relatively low in Western populations, often due to concerns about mercury or simply dietary preferences.¹⁷
Rather than focusing on symptoms of deficiency, which can be vague and non-specific, guidance tends to focus on ensuring regular intake through diet or supplementation.
You may be more likely to have lower omega-3 intake if you:

Rarely or never eat oily fish
Follow a vegetarian or vegan diet
Avoid seafood due to taste or pregnancy-related aversions

This is why understanding your options – both dietary and supplemental – can help you make informed choices that suit your lifestyle during pregnancy.
Have questions about nutrition during pregnancy? Find practical guidance for eating well throughout every trimester.

Best omega-3 foods and supplements for pregnancy

Best food sources of omega-3 in pregnancy
Oily fish (recommended):

Salmon
Sardines
Mackerel
Herring

These are the richest natural sources of EPA and DHA. NHS guidance recommends 1–2 portions of oily fish per week during pregnancy, but no more than this.¹⁸
Other sources:

DHA-enriched eggs
Fortified foods (such as certain dairy or plant milks)
Seaweed and algae (natural sources of DHA)

Plant-based sources (ALA):

Chia seeds
Flaxseeds
Walnuts

While nutritious, these provide ALA rather than DHA, and conversion to DHA in the body is limited.

Omega-3 supplements in pregnancy

For those who struggle to meet omega-3 needs through diet alone, supplements can be a helpful option.
Common types include:

Fish oil supplements (providing EPA and DHA)
Algal oil supplements (plant-based DHA suitable for vegans)

When choosing a supplement:

Look for products specifically labelled as suitable for pregnancy
Choose brands that are third-party tested for purity
Ensure they are low in contaminants such as mercury

When choosing a supplement, it’s important to be aware that not all omega-3 products are suitable during pregnancy. For example, cod liver oil should be avoided, as it contains high levels of vitamin A (retinol), which is not recommended during pregnancy.¹⁹
Always check with your midwife or GP before starting a new supplement.

Is fish oil safe during pregnancy?

Fish oil supplements are generally considered safe during pregnancy when sourced from reputable manufacturers and taken as directed.
Unlike whole fish, purified fish oil supplements contain very low levels of contaminants such as mercury, as these are typically removed during processing.
However, it’s still important to follow guidance around fish consumption:²⁰

Limit oily fish to no more than 2 portions per week
Avoid high-mercury fish such as shark, swordfish, and marlin
Vary your seafood choices where possible

Mercury exposure during pregnancy is important to minimise, as it can cross the placenta and has been linked to developmental concerns in babies.21,22 , Following NHS guidance helps balance the benefits of omega-3 intake with safety considerations. You should always check with your midwife or GP before starting a new supplement.

Key takeaways: omega-3 and pregnancy

Omega-3 fatty acids are essential fats, meaning they need to come from food or supplements.
DHA is especially important during pregnancy because it supports your baby’s brain, eye and nervous system development.
Oily fish is one of the richest natural sources of EPA and DHA, but pregnant women should follow UK safety limits.
Vegetarian or vegan diets may need extra planning because plant ALA converts poorly to DHA.
Algal oil can provide DHA without fish and may be suitable for people following a plant-based diet.
Cod liver oil should be avoided in pregnancy because it can contain high levels of vitamin A.

Frequently asked questions about omega-3 in pregnancy

What is the most important omega-3 during pregnancy?

DHA is usually considered the most important omega-3 during pregnancy because it is a key structural fat in the brain and retina. Your baby’s DHA needs increase as the brain and eyes develop, particularly later in pregnancy.

Can I get enough omega-3 without eating fish?

It may be harder to get enough DHA without fish because plant foods provide ALA, which converts poorly to DHA. If you are vegetarian, vegan or avoiding fish, an algae-based DHA supplement may be worth discussing with your GP or midwife.

How much oily fish can I eat while pregnant?

UK guidance recommends including fish as part of a balanced diet, but limiting oily fish to no more than two portions per week during pregnancy. Shark, swordfish and marlin should be avoided because they can contain higher levels of mercury.

Is cod liver oil safe in pregnancy?

Cod liver oil is not recommended during pregnancy because it can contain high levels of vitamin A in the form of retinol. If you want to take an omega-3 supplement, choose one labelled as suitable for pregnancy and check with your GP or midwife first.

Conclusion

Omega-3 fatty acids, particularly DHA, play an important role during pregnancy, supporting your baby’s brain and eye development while contributing to your own overall wellbeing.
While oily fish remains one of the best sources, not everyone finds it easy to include regularly and it’s important to stay within recommended limits during pregnancy. In these cases, a combination of dietary sources and carefully chosen supplements can help support your intake, whether you eat fish or follow a plant-based approach.
As with any changes during pregnancy, it’s always a good idea to speak to your GP or midwife before introducing new supplements, so you can make choices that feel right for you.

For more support, explore Health & Her’s expert-led pregnancy guides and tools, designed to help you feel informed and confident at every stage of your pregnancy journey.

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