Docosahexaenoic acid (DHA) is a type of omega-3 fatty acid that is important for good health. Taking DHA in supplement form during pregnancy may help support healthy fetal growth.

This article explores prenatal DHA supplements, the health benefits of DHA during pregnancy, its potential side effects and recommended dosages, how to choose a quality supplement, other ways to receive DHA, and when to speak with a doctor.

Share on Pinterest
AndreyPopov/Getty Images

Prenatal DHA is a type of vitamin or supplement containing the omega-3 fatty acid DHA.

Most DHA supplements come from:

  • cod liver oil
  • krill oil
  • fish oil within fatty fish such as salmon, tuna, herring, mackerel, and sardines
  • algae oil

In some cases, prenatal DHA pills or liquids only contain DHA. However, prenatal DHA supplements or vitamins may also carry other nutrients, including:

All forms of omega-3 fatty acids are vital for health, especially during pregnancy. People must consume omega-3 fatty acids through foods or supplements because the body does not naturally produce them.

The omega-3 DHA is critical to the healthy development of the eyes, nervous system, and brain.

Much research suggests a positive link between DHA consumption and visual and cognitive function. However, a recent 2019 study found no difference in cognitive abilities or visual acuity in infants whose parents consumed DHA during the second and third trimesters of pregnancy. Researchers suggest the DHA intake was not high enough to produce results or that the testing methods to check for cognitive and visual acuity were not sensitive enough.

Consuming omega-3 fatty acids during pregnancy also seems to lower the risk of premature birth.

Additionally, older research links DHA with improved fertility and reproductive egg health.

The benefits of DHA supplementation may also extend to pregnant people. A 2020 review suggests that DHA may improve mood during late pregnancy and early postpartum.

People who are allergic or intolerant to seafood, nuts, soy, milk, or other food allergens should ensure DHA products do not contain these allergens or pass through a facility that processes them.

Side effects from taking DHA tend to be minor or mild, including:

In some cases, DHA can also interact negatively with supplements or medications, such as the anticoagulant warfarin.

According to the National Institutes of Health (NIH), there is no established recommendation regarding DHA dosage. However, experts recommend pregnant people consume 200 milligrams (mg) of DHA per day. Additionally, most prenatal supplements contain 200 mg of DHA.

In terms of dietary consumption, pregnant people should aim to eat a minimum of two servings of low mercury shellfish or fish per week before and during pregnancy and while nursing. One serving of fish contains 9–12 ounces (oz).

Most people living in the United States do not get enough EPA and DHA. Levels of these fatty acids also reduce during pregnancy, as DHA transfers to the fetus through the placenta. That means individuals must consume more of the substance to have sufficient levels themselves.

However, the Food and Drug Administration (FDA) recommends against consuming more than 3 grams (g) per day of EPA and DHA combined, which includes up to 2 g per day from dietary supplements. DHA consumption higher than this may cause bleeding issues and negatively impact the immune system.

Picking a high-quality prenatal DHA is important — low-quality, unverified products can contain toxins and contaminants. Most advanced refining systems remove almost all of these harmful compounds.

Therefore, it is important to pick products with packaging that indicates a reputable third-party organization or lab has verified the product’s quality and purity in particles per trillion levels.

Many trustworthy organizations set standards that assess the quality and purity of fish oil products, such as the following:

  • Council for Responsible Nutrition
  • European Pharmacopoeia
  • Global organization for EPA & DHA omega-3s

Be wary of products stated to exceed the standard maximum allowances of harmful heavy metals, toxins, and oxidation set by one or more of these organizations.

It is also a good idea to pick products proven in clinical trials to be safe and effective. A person can find this information on the pamphlet or packaging that comes with the supplement or the manufacturer’s website.

People who follow vegetarian diets, have a seafood allergy, or do not wish to eat or buy seafood can consume products containing DHA that derives from types of algae or seaweed. The omega-3 fatty acids in fish actually come from microalgae, which accumulate in the tissues of fish that eat them.

Many products claim to contain vegetable sources of DHA.

However, nonmarine plants do not actually contain DHA — instead, they contain the omega-3 fatty acid alpha-linolenic acid (ALA), which the body converts to EHA then DHA in small amounts. Pregnant people should consume at least 1.4 g of ALA per day.

Because seafood can contain heavy metals and toxins, it may be safer for pregnant people to consume foods fortified with DHA, such as certain:

  • yogurts
  • milk
  • eggs
  • soy products
  • juices
  • infant formulas

DHA only occurs naturally in certain species of fish, some seafood, chicken, and eggs. Studies show the benefits of consuming moderate amounts of seafood during pregnancy tend to outweigh the potential risks, especially if consuming high-quality, low-mercury seafood.

Safe seafood options for pregnant people and their average DHA dose per 3-oz serving include:

  • farmed Atlantic salmon: 2.24 g
  • wild Atlantic salmon: 1.22 g
  • Atlantic herring: 0.94 g
  • canned sardines: 0.74 g
  • Atlantic mackerel: 0.58 g
  • canned pink salmon: 0.63 g
  • wild rainbow trout: 0.44 g
  • sea bass: 0.47 g
  • wild Eastern oysters: 0.23 g
  • light canned tuna: 0.27
  • flounder: 0.2–0.5 g
  • crab: 0.2–0.5 g
  • catfish: 0.02 mg or less
  • shrimp: 0.12 g
  • tilapia: 0.11 g
  • Pacific cod: 0.10 g
  • lobster: 0.07 g
  • scallops: 0.09 g

Additionally, one cooked egg tends to contain roughly 0.03 g of DHA, while 3 oz of roast chicken breast typically contains 0.02 g of DHA.

Pregnant people should only consume one serving per week of seafood containing moderate levels of mercury and other toxins. These types of seafood include:

  • albacore and yellowfin tuna
  • bluefish
  • carp
  • Chilean sea bass
  • halibut
  • mahi-mahi
  • snapper
  • stipped ocean bass
  • sablefish
  • monkfish
  • rockfish
  • grouper
  • sea trout

Pregnant people should also avoid species of seafood with higher mercury levels, such as:

  • marlin
  • shark
  • swordfish
  • tilefish
  • bigeye tuna
  • king mackerel
  • orange roughy

Look for fish or fish products that carry the “Safe Catch” logo, which shows the seafood has met purity and quality standards.

Pregnant people should also limit their consumption of seafood that friends or family physically catch to one serving per week and not eat any other fish that week. Individuals should also avoid consuming seafood if there are safety or health advisories in the area where a person has caught the seafood.

Pregnant people can discuss with their doctor, dietician, or nutritionist about what supplements or dietary changes they should make to keep themselves and their developing baby safe and healthy.

People taking prescription or over-the-counter medications or supplements should also consult with a healthcare professional before taking DHA supplements. They can speak with a doctor if they cannot tolerate DHA supplements or DHA-rich foods.

Getting enough DHA may be important for healthy fetal development. It may also positively impact aspects of pregnancy and a pregnant person’s mood.

People should pick DHA supplements that undergo independent testing and certification of the product’s safety and purity by a reliable organization.

To avoid negative interactions, individuals should talk with a doctor before taking DHA when also taking other medications or supplements.