The many benefits of taking fish oil supplements during pregnancy

Omega-3 fatty acids are one of the most vital nutrients for your unborn baby.
Written by
Rachael Belfield
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Last updated on
May 16, 2024
min read
Fish Oil During Pregnancy: Benefits & Best Foods | Kin Fertility
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While having a balanced, varied diet during pregnancy is important for you and your bub, sometimes the all-encompassing effects of morning sickness and lethargy will have us reaching for instant noodles and peanut butter instead of salmon and steamed greens every day.

If you're not getting a decent amount of critical nutrients from your diet, you can look at pregnancy supplements. Most pregnancy supplements are designed to give your baby the best possible chance of absorbing the right amount of vitamins and minerals.

In the large and growing number of pregnancy supplements available in pharmacies and online, omega-3 fatty acids are often overlooked as an optional extra, or not as important as other nutrients.

But there is a well established and expanding understanding among clinicians, backed by robust trials and studies, that omega-3 fatty acids are actually critical for your baby's brain development and should always be incorporated into your diet while pregnant.

Omega-3s can be found in a variety of tasty foods, but also as fish oil supplements.

What are fish oil supplements?

Fish oil is, essentially, a healthy fat extracted from fish tissue that is packed with omega-3. Fish oil isn't distilled from just any fish, but oily fish such as herring, tuna, anchovies and salmon.

Fish oils contain two long-chain omega-3s called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which researchers suggest are the two most important of the omega-3s and found naturally in fish.

Studies have shown that EPA and DHA are important for foetal development and can actually influence child development, too. They support a range of different brain and sight functions including neuronal, retinal, and immune functioning.

They're also important for cardiovascular function, blood pressure balancing, reducing inflammation, minimising artery disease and reducing the risk of stroke.

Dieticians suggest eating oily fish two to three times per week to meet your optimum omega-3 requirements, but this can be difficult to achieve without extra help.

Quality fish oil is a generally safe, effective and easy way to ensure you are getting enough omega-3 fatty acids in your diet. But not all fish oil supplements are created equally. If you read the label at the back of a fish oil supplement bottle, ensure it actually contains EPA and DHA.

A fish oil supplement may say on the front that it contains 1,000 mg of fish oil per capsule. However, on the back you’ll read that EPA and DHA are only 320 mg, when the recommended amount is actually between 400mg to 900mg of EPA and DHA a day.

It's recommended that pregnant women go on the higher end of this to meet their nutritional needs as well as their baby's development.

Why are omega-3 fatty acids important in pregnancy?

Omega-3 is a generic term that refers to a category of lipids (fatty acids) that are essential to a baby’s brain development. Omega-3s (docosahexaenoic acid and eicosapentaenoic acid) can’t be synthesised in the body, and need to be sought from our diets or with fish oil supplementation.

But, the standard western diet is severely deficient in these critical nutrients. On top of this, pregnant women become depleted in omega-3 fatty acids because the foetus is absorbing most of it.

This is why fish oil supplementation is excellent not just for developing babies, but for making sure mum's muscles and heart stay strong, too.

You can increase your omega-3 fatty acids intake by eating huge amounts of low-mercury fish, but it’s much easier with a EPA and DHA rich fish oil.

What are the benefits of fish oil during pregnancy?

There is a huge body of research that includes large and robust trials that have looked at how to best help your baby develop well in the womb. Omega-3 fatty acids almost always come up as one of the vital nutrients to help a foetus develop into a healthy, happy baby.

Baby brain and retina development

Science is always looking at ways to support brain development in babies, and omega-3s often come up as critical tools for pregnant women. DHA is the critical component of cell membranes in the brain for neural function, retina growth and neurotransmitter metabolism.

A pregnant women's consumption of DHA-rich fish oil means DHA passes into the bloodstream and reaches the baby through placental transfer.

Babies in the womb need omega-3 fatty acids, especially DHA, for the development of their central nervous system and eyes.

DHA, even more so than EPA, is particularly important for foetal development of the brain during the third trimester and up to 18 months of life, so it's great for breastfeeding mothers, too, as DHA is passed from a mum to her baby through milk.

In the third trimester, the baby's brain undergoes a rapid growth spurt, ramping up DHA absorption from the mother's supply. Babies who are born preterm miss out on a lot of the important brain development, which can be concerning for their mental and physical development.

Mum is also then in danger of becoming deficient in this important nutrient. Low maternal DHA at birth has actually been associated with an increased risk of postpartum depression.

Keeping up with your DHA count is extremely important for helping these critical developmental periods along, not just for your baby but for yourself.

Birth weight

There is a small collection of islands above Scotland and below Iceland called the Faroe Islands. There, the Faeroese give birth to some of the heaviest babies in the world!

This has been attributed to the high prevalence of lovely, oily, omega-3 rich fish in their diets that work to help babies grow. Omega-3 supplements are also linked with lower rates of preterm births and a larger baby head circumference.

Toddler development

Back in 2006, a study took place in Perth, WA, looking at the link between a mother's intake of fish oils rich in EPA and DHA and cognition at two years of age.

Pregnant women were given either fish oil or olive oil. At two and a half years of age, children in the fish oil supplemented group had higher scores for eye and hand coordination compared with those in the olive oil group.

Eye and hand coordination scores and other tests of mental acuity were strongly linked with the women who took fish oil supplements in pregnancy.

Fish oil studies like this indicate the that pregnant and lactating women will pass on the market benefits of fish oil to their kids. But, this is only one piece of evidence.

There are too few studies to suggest that taking fish oils during pregnancy will automatically make your child smarter, or will be a one-way ticket to child intelligence. However, we can draw reasonable conclusions that children benefit hugely from its inclusion in your diet while pregnant.

What foods are high in omega-3 fatty acids?

We've mentioned that omega-3 fatty acids can only be absorbed into the body via a person's diet.

If you are wanting to increase your intake outside of fish oil supplements, you can find them in your supermarket in the fish, nuts and veggie sections!


Certain fish are extremely high in omega-3s, but it depends on the fish species. Fish that live in the colder climates including salmon, mackerel, tuna, herring and sardines.

It's quite fascinating as cold water-dwelling fish have a high number of omega-3s in their diets too, and the oily fat and lean tissue that it turns into is what keeps them warm and fluid to swim in these climates.

Tinned tuna and salmon are such easy and delicious additions to any salad, sandwich or pasta dish and are a great way to get your omega-3 fix. The only downside to eating cold water fish in pregnancy is the risk of consuming high levels of mercury, which is often present in these lovely, oily fish.

The research indicates that pregnant women should stick to less than three portions of fish per week to minimise the risk of mercury poisoning.

Luckily, the amount of mercury present in most fish oil supplements is negligible, so it may be a safer option for you. As we said, always keep your doctor informed of any dietary changes you make in pregnancy.

Nuts and seeds

Eating fish isn't the only way to get your omega-3s. Most nuts and seeds are a wonderful, easy and healthy snack to have on hand when you're on the go or looking for an afternoon pick-me-up.

For omega-3s, you'll want to incorporate flaxseed, chia seeds and walnuts into your diet.

Sprinkle chia seeds or ground flaxseed onto your morning porridge or roast walnuts to add to your salad or pasta!

Plant oils

We're talking flaxseed oil (otherwise known as linseed oil), soybean oil and canola oil.

The great thing about these is that you can add these to your meals instead of olive oil if you're looking for an omega-3 burst.

Fortified foods

‌Fortified foods have added vitamins, minerals and other micronutrients added during food production. You may have seen eggs in the shops fortified with vitamin D — this is a public health benefit as many people are vitamin D deficient.

In recent years, a large number of omega-3-fortified food products have reached the market ranging from certain meats, eggs, dairy products, cereals, cereal bars, and infant formulas.

Omega-3 consumption isn't only for breastfed babies: your little bub can enjoy the benefits of it with DHA fortified formula too.

If you're relying on fortified foods only to reach your required omega-3 intake, ensure you check the labels to see the EPA and DHA levels of all the packaged foods you eat to make sure you're getting enough.

What about other kinds of omega-3 dietary supplements?

If you're vegan or vegetarian, you would rightly want to stay away from fish oil supplements. Other omega-3 supplements include krill oil and algal oil, vegetarian source that comes from the extremely DHA-dense algae.

The bottom line on fish oil in pregnancy

Always check with your doctor before you start any new supplements, but fish oil is widely known to be safe and effective for absorption in utero. If you're looking to increase your omega-3 intake by eating fish, this is great!

But make sure you are aware of mercury levels and the effect it can have on your baby and stick to just one to two serves of fish a week.

The takeaways:

  • Fish oil in pregnancy supports child retina and brain development. It also can have an effect on birth weight and can minimise the occurrence of preterm birth.
  • It is a safe, convenient and effective option for pregnant women and this safety is backed by a huge amount of scientific evidence.
  • Stick to less than three portions of fish per week in your diet.
  • It's important to have a varied diet to help support the many, many needs of your unborn baby. Taking omega-3s will certainly assist child brain development, but it is not the only supplement you should be relying on.
  • Speak to your doctor about whether or not fish oil supplementation is right for you.

We know pregnancy can be a little overwhelming — but it doesn’t have to be. Kin's Pregnancy Checklist consists of bite-sized checklist items personalised to your pregnancy journey. Approved by fertility specialists and OBYGN approved, you'll feel prepared to tackle each day as it comes and enjoy the process, rather than get lost in it.


  1. Brown B, Wright C. Safety and efficacy of supplements in pregnancy [published correction appears in Nutr Rev. 2020 Sep 1;78(9):782]. Nutr Rev. 2020;78(10):813-826. doi:10.1093/nutrit/nuz101
  2. Greenberg JA, Bell SJ, Ausdal WV. Omega-3 Fatty Acid supplementation during pregnancy. Rev Obstet Gynecol. 2008;1(4):162-169.
  3. Olsen SF, Hansen HS, Sørensen TI, Jensen B, Secher NJ, Sommer S, Knudsen LB. Intake of marine fat, rich in (n-3)-polyunsaturated fatty acids, may increase birthweight by prolonging gestation. Lancet. 1986 Aug 16;2(8503):367-9. doi: 10.1016/s0140-6736(86)90055-3. PMID: 2874370.
  4. Vollet K, Ghassabian A, Sundaram R, Chahal N, Yeung EH. Prenatal fish oil supplementation and early childhood development in the Upstate KIDS Study. J Dev Orig Health Dis. 2017;8(4):465-473. doi:10.1017/S2040174417000253
  5. Joseph R. Hibbeln, Seafood consumption, the DHA content of mothers’ milk and prevalence rates of postpartum depression: a cross-national, ecological analysis, Journal of Affective Disorders, Volume 69, Issues 1–3, 2002, Pages 15-29, ISSN 0165-0327,
  6. Carlson SE, Colombo J, Gajewski BJ, et al. DHA supplementation and pregnancy outcomes. Am J Clin Nutr. 2013;97(4):808-815. doi:10.3945/ajcn.112.050021
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