Beyond the Prenatal Vitamin: How Much DHA Should You Take During Pregnancy?

Eating a balanced diet and taking prenatal vitamins are important habits during pregnancy. Some vitamins and nutrients, like folic acid, are part of nearly every prenatal vitamin. But others, like omega-3 fatty acids (omega-3s), may not always be included — even though they’re an important supplement you should take during pregnancy.

But before you pick up a bottle of omega-3s from the supplements aisle, you may still have a few questions. You may wonder: What are omega-3s, and how much do you need to take? Or, what’s docosahexaenoic acid (DHA), and how much should you take in pregnancy? Let’s explore vitamins in pregnancy and which ingredients — like omega-3s and DHA — you should look for.

What are omega-3 fatty acids?

Omega-3s are polyunsaturated fatty acids. They support many of the body’s systems and organs, including the:

• Lungs

• Heart 

• Immune system

• Brain

• Eyes

The human body can’t make omega-3s on its own, so you have to get them from foods or supplements. The three main types are:

• Alpha-linolenic acid (ALA)

• Eicosapentaenoic acid (EPA)

• Docosahexaenoic acid (DHA)

EPA and DHA are considered “active” forms of omega-3s. This means they’re ready to be used by the body. ALA isn’t an active omega-3. The body must break down ALA into EPA and DHA in order to use it.

What is the difference between DHA, fish oil, and omega-3s?

Keeping the terms straight can be a bit tricky. Here’s what you need to know:

• Omega-3s are fatty acids found in foods and supplements.

• DHA is one type of omega-3 fatty acid.

• Fish oil is a supplement people take to get more omega-3 fatty acids.

Why are omega-3s and DHA important during pregnancy?

During pregnancy, there’s a higher need for omega-3s to support both the pregnant woman and growing baby. 

EXPERT PICKS: WHAT TO READ NEXT

• Prenatal vitamin basics: Learn what’s in them and why they’re so important.

• Getting prenatal care: Even if you’re perfectly healthy, there are many reasons why seeing a healthcare professional regularly throughout your pregnancy is a good idea.

• Medications to avoid: If you’re pregnant, or could be soon, be aware that certain medications can be harmful to a developing fetus.

Benefits to the growing baby

Omega-3s are most important for the growing baby. This is true for a few reasons:

• They’re needed for healthy brain development. DHA is particularly important for this.

• Getting enough omega-3s during pregnancy may also lower the risk of preterm birth (less than 37 weeks) and low birth weight.

• Women with gestational diabetes may have lower DHA levels in umbilical cord blood, which may lead to lower DHA levels in newborns. Research suggests high-dose DHA supplementation during pregnancy can improve these levels.

Some studies have noted a link between higher DHA levels in mothers and fewer cases of autism spectrum disorder in their children. Other research suggests that eating fish — rather than taking omega-3 supplements — may be more important. Overall, study results are inconsistent, and there’s not enough evidence to suggest omega-3s can prevent the risk of autism spectrum disorder.

Benefits to the pregnant woman

Many studies have investigated the possible benefits of omega-3s for pregnant women. Observational studies have found links between omega-3s and the reduced risk of:

• Postpartum depression

• Preeclampsia

• Gestational diabetes

But cause-and-effect relationships haven’t been established. So, while research is ongoing, there’s currently not enough evidence to suggest omega-3s can reduce these risks. The greatest benefit is the reduced risk of delivering early.

What dose of omega-3s is best during pregnancy?

Most experts recommend at least 250 mg per day of DHA and EPA for all adults. It’s best to get omega-3s from food when possible. This equates to roughly 8 oz to 12 oz of fish per week during pregnancy. But make sure to opt for fish that are low in mercury, especially while you’re pregnant (more on this below).

Experts recommend extra omega-3s during pregnancy — an additional 200 mg per day. They also recommend higher amounts (600 mg to 1,000 mg daily) for those who don’t get enough omega-3s through diet. Some studies have shown that higher doses (up to 1,000 mg) may be beneficial, in terms of reducing the risk of preterm birth.

But how much omega-3 is too much? The upper limit isn’t completely clear. In pregnant women, doses of up to 1,000 mg of DHA or 2,700 mg of DHA/EPA have been used without significant side effects. When they do appear, common side effects of omega-3s include:

• Unpleasant taste

• Smelly breath and sweat

• Upset stomach

Where can I find omega-3s?

Omega-3s are found in both plant- and animal-based foods, as well as OTC supplements. Many prescription prenatal vitamins also contain them. Keep in mind that foods and supplements have varying amounts of DHA in them. Just because a food or supplement is high in total omega-3s doesn’t mean it’s high in DHA. You’ll have to read the label closely to make sure.

Food sources

You may be surprised to learn that oily fish isn’t the only source of omega-3s. There are plenty of ways to get enough without eating fish. For example, certain plant oils — like flaxseed and canola — are high in ALA. Fortified eggs and grass-fed beef are other options. 

Some examples of the typical amount of omega-3s in food sources include:

• Canola oil (1 tbsp): 1,300 mg of ALA

• Chia seeds (1 oz): 5,000 mg of ALA

• Atlantic salmon (3 oz): 1,200 mg of DHA and 590 mg of EPA

• Light tuna (3 oz): 170 mg of DHA and 20 mg of EPA

Keep in mind that some fish may be high in mercury. Too much mercury can negatively affect a baby’s developing brain. So it’s a good idea to consume seafood that’s low in mercury and high in DHA. Some examples include:

• Shrimp

• Salmon

• Scallops

• Light tuna

Supplements 

Omega-3 supplements come from both plant and animal sources. Some of these are:

• Animal-based: fish oil, krill oil, and cod liver oil

• Plant-based: algae oil and flaxseed oil

One type of supplement isn’t necessarily better than another. But different supplements have varying omega-3s. For example, fish oil pills contain DHA and EPA while algae oil is mostly DHA. 

How to choose an OTC supplement

First, determine the amount of omega-3s you need. If you aren’t sure how much you’re getting in your diet, or you’re having trouble choosing a supplement, ask your pharmacist, primary care provider, or obstetrician. They can help you figure out what you need.

Next, be sure to read the label when browsing supplements. This will show you the amount of omega-3s in each tablet. Amounts can vary between brands, and don’t forget there may be additional omega-3s in your prenatal vitamin.

Look for supplements that are verified by independent organizations, such as:

• U.S. Pharmacopeia (USP): Look for a “USP-verified” mark on the bottle. This indicates that the supplement contains what it says it does. You can also search for USP-verified products directly from its website.

• National Sanitation Foundation (NSF): Products that pass NSF international testing also have a unique mark on the bottle. You can search for NSF-verified supplements.

• Natural Products Association (NPA): The NPA gives certification to supplements adhering to “good manufacturing practices.”

When should you start taking omega-3 supplements? 

If you don’t think you’re getting enough omega-3s from your diet, it’s a good idea to start taking omega-3s as soon as you become pregnant. You can also add them to your routine as soon as you begin trying to conceive. Experts recommend starting omega-3 supplementation by the second trimester.

Can I take omega-3s with other medications?

Omega-3 fatty acids don’t have significant interactions with other medications. But at high doses, they may increase your risk of bleeding. So it’s important to discuss this with your healthcare team, especially if you take blood-thinning medications.

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Written by:

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP, has over a decade of experience as a pharmacist, professor, and researcher. She currently practices as a clinical pharmacist at Buffalo General Medical Center.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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