How Much Omega-3 Fatty Acids Supplementation During Pregnancy?

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Medically reviewed by Kimberly Langdon, MD

Omega-3 To Pregnancy

Diet and supplementation play a vital role in ensuring pregnant women obtain sufficient nutrients for optimum growth and development of the fetus. Omega-3 fatty acids are polyunsaturated essential fatty acids necessary for fetal brain and eye neurodevelopment. 

Many omega-3 supplements, such as fish oils, have different EPA and DHA content. As EPA and DHA contribute to the healthy development of the fetus, consuming adequate amounts is essential for pregnant women.

How much omega-3 fatty acids supplementation is required during pregnancy, what is the recommended daily dose through diet, and what sources are rich in EPA and DHA?

How Much Omega-3 Fatty Acids Supplementation During Pregnancy?

Consensus guidelines recommend that pregnant women take omega-3 supplements (containing at least 200 mg DHA per day) before, during and after pregnancy. Consuming two seafood servings per FDA guidelines contributes to this amount, and that most fish oil supplements and prenatal vitamins contain at least 200 mg DHA per day.

Omega-3 Fatty Acid Types

Optimal fetal neurodevelopment depends on many essential nutrients, including omega-3 fatty acids. These are long-chain essential fatty acids as the body cannot produce them independently, so it must acquire sufficient amounts through dietary sources and supplementation. 

There are three main types of omega-3 fatty acids:

  • Alpha-linolenic acid (ALA)
  • Eicosapentaenoic acid (EPA)
  • Docosahexaenoic acid (DHA)

ALA are short-chain fatty acids found in abundance in plant-based sources such as flaxseed and canola oils, whereas EPA and DHA are longer chains found in fish oils. In the body, ALA converts to EPA, which subsequently converts to DHA.

Role of DHA 

DHA is a major structural lipid in the brain and retina’s cell membranes, accounting for most omega-3 fats in the brain and retina. Because of this, DHA is essential for fetal development of the brain and retina, particularly during the last trimester, as the fetus accumulates 50 to 70 mg DHA per day

Therefore, pregnant women must consume enough omega-3 fatty acids as the fetus can only acquire DHA via the placenta from maternal consumption. They also need to consider DHA content when selecting omega-3 fatty acid supplements as they can vary. 

Dietary Doses of Omega-3 Fatty Acids

There is inconsistency in daily recommended amounts of EPA and DHA during pregnancy, depending on the potential benefit of the mother and fetus.

The US Food and Drug Administration (FDA) recommends a minimum of 250 to 500 mg of combined EPA and DHA per day for healthy adults with an additional 200 mg of DHA during pregnancy, and consensus guidelines recommend at least 200mg DHA per day in pregnant women.

Some studies suggest pregnant women should consume 650 mg per day of omega-3 fatty acids (300 mg DHA) through various sources such as seafood, vegetable oils and supplements. This is consistent with guidelines of at least 200 mg DHA per day during pregnancy. 

Consuming seafood provides high levels of omega-3 fatty acids, particularly EPA and DHA. However, seafood also contains neurotoxins such as mercury and polychlorinated biphenyls (PCBs), which can be detrimental to the growing fetus. These potentially dangerous contaminants can accumulate more in fish meat than in fish oil.

Therefore the FDA recommends limiting seafood to 2 servings per week (no more than 340 g or 12 oz) during pregnancy to limit fetal exposure to neurotoxins. But despite this allowance, many pregnant women in the western world still consume insufficient omega-3 fatty acids

Pregnant women may be confused about seafood serving sizes or fear the adverse effects of fetal neurotoxin exposure so that they may omit seafood entirely during pregnancy. Taking omega-3 fatty acid supplements may bridge the gap needed for healthy fetal growth. 

Omega-3 Fatty Acid Supplementation

Fish Oil Supplements

EPA and DHA content in fish oil supplements vary according to manufacturers, but generally, EPA and DHA make up one-third to one-half of the omega-3 fatty acids in the capsule. So 1000 mg of omega-3 fatty acids contain typically 300 to 500 mg of EPA and DHA. 

Fish oil supplements contain relatively low amounts of contaminants and are therefore safe to consume. They are also free from serious side effects that may influence compliance other than an unpleasant taste for some.

Cod liver oil, however, is not a recommended supplement of EPA and DHA during pregnancy, because of its high vitamin A content, unlike other fish oils. High levels of vitamin A during pregnancy have been associated with congenital birth defects

Prenatal Supplements

Prenatal vitamins can be taken before and during pregnancy, typically containing 200 to 300 mg DHA and varying amounts of other vitamins.

Omega-3-Enriched Eggs

Hens that feed on omega-3 supplements such as flax seeds produce eggs with a higher omega-3 content than conventional eggs, containing up to 150mg DHA per egg. 

Possible Benefits of Omega-3 Fatty Acids

Improve Fetal Brain and Retina Neurodevelopment

Studies show consuming omega-3 fatty acids during pregnancy, particularly EPA and DHA, improves fetal neurodevelopment of the brain and retina and plays a significant role in the growth and development of many organ systems, notably the central nervous system. Research suggests children whose mothers consumed omega-3 fatty acids during pregnancy could see more clearly and had higher verbal intelligence scores.

Reduce Risk Of Preterm Birth

Consuming omega-3 fatty acids in pregnancy may also improve pregnancy outcomes by increasing the gestational period, reducing the risk of preterm births and increasing birth weight. A study compared pregnant women who took fish oil supplements containing DHA, olive oil or no supplement showed an increase of 4 day gestation and birth weight in those who took fish oil supplements .

Reduce Pregnancy-Related Depression

Research also suggests that consuming omega-3 fatty acids during pregnancy may reduce the risk of pregnancy-related and postpartum depression.

Sources of Omega-3 Fatty Acids

Marine Sources

Seafood such as high-fat, cold-water fish is rich in EPA and DHA, as they mainly feed on algae and crustaceans that contain large amounts of omega-3 fatty acids. Following the FDA recommendation of no greater than two seafood servings per week, pregnant women must carefully consider the seafood options available depending on varying neurotoxin levels. 

Methylmercury is a neurotoxin that accumulates in aquatic food chains and is known to cross the placenta. However, its effect on fetal development is unclear as studies show conflicting results. 

Some studies suggest children exposed to high mercury levels as a fetus are born with a lower IQ, while others found no difference in IQ test. Still, fear and confusion over mercury levels in seafood have resulted in pregnant women avoiding it entirely, which may provide inadequate DHA for the developing fetus. 

Research suggests pregnant women should avoid consuming large, long-living predatory fish that contain high levels of mercury, such as shark, swordfish and king mackerel. Instead, opting for smaller, short-lived seafood with lower mercury levels, such as shrimp, salmon and sardine. 

Plant-Based Sources

Vegetable oils such as flaxseed, canola and soybean oil are rich in ALA. However, ALA needs to convert to EPA and DHA to be biologically active in the body, but the amounts converted are insignificant and far below the recommendations during pregnancy. Therefore, it is far more effective to directly consume EPA and DHA sources, such as seafood or supplements. 


  • Omega-3 fatty acid intake during pregnancy is essential for fetal neurodevelopment, particularly of the brain, eyes and central nervous system.
  • All pregnant women should follow recommendations for increased omega-3 fatty acid uptake of at least 200 mg DHA per day through various sources, such as two servings of appropriate seafood per week and additional omega-3 fatty acid supplementation.
  • Those who prefer not to consume seafood or are concerned about neurotoxins can rely wholly on omega-3 fatty acid supplementation products such as fish oil capsules, prenatal vitamins and DHA-enriched eggs.
  • Although other sources of omega-3 fatty acids, such as vegetable oils, are high in ALA, they provide insignificant EPA and DHA to contribute sufficiently to the daily recommendation.
  • With the many health benefits of omega-3 fatty acids, particularly the effect of DHA on the developing fetus and possibly increasing gestational period and reducing pregnancy-related and postpartum depression, doctors often recommend taking a DHA supplement before, during and after pregnancy.


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Medically reviewed by:

Christina Cheung holds a Master’s of Pharmacy from the University of Bath (UK) and is a freelance writer specializing in medicine and science. With over a decade of experience as a community and hospital pharmacist both in the UK and abroad, she has dealt first-hand with patients facing medical difficulties and decisions. She now writes to promote medical health and wellness to better the community. Christina also has a published science blog with a passion for inspiring and encouraging medicine and science for kids and students. While not writing, she can be found strolling through the country parks with her family and pet dog.

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