Is Fish Oil Safe During Pregnancy? How Much Should I Take?

You may already be taking fish oil prior to conceiving since there are many known benefits.

However, taking a supplement while pregnant can be worrisome for some mothers, because many supplements aren’t always pregnancy-safe.

You may have wondered if there are any additional benefits for the baby, and what the correct dose might be.

Fish oil is a safe supplement for women to take for the duration of their pregnancy. Medical providers recommend fish oil as the omega-3 fatty acids are necessary to support the baby’s brain and eye development. Fish liver oils, however, should be avoided.

Not all supplements are created equal, however, and women should be careful to choose brands that meet quality standards, provide adequate DHA, and are not sourced from fish livers to ensure the greatest amount of safety and benefit.

There are also some safety considerations, as fish oil does come from fish, after all.

I’ll provide the facts on cod liver oil, mercury content, safe doses, and provide some examples of better brands to search for.

Is Fish Oil Safe During Pregnancy?

Fish oil, also sometimes labeled as omega-3 fatty acids, is usually taken as a capsule or gel-filled caplet.

Fish oil is so popular, in fact, that it’s often recommended by doctors and is generally regarded as safe for most adults (source: Mayo Clinic).

When it comes to pregnancy, fish and seafood products should be consumed with caution. Many women are advised to limit their consumption of some types of fish and seafood because of the mercury – but this doesn’t apply to fish oil.

The mercury of fish oil content does vary from brand to brand.

A 2008 study found that the fish oil pills tested contained slightly more mercury than fish. The serving size of fish oil, however, is smaller than fish fillet so the mercury level is still low enough to be safe (source: Reviews in Obstetrics and Gynecology).

According to the American Pregnancy Association (APA), the refining process used to make high-quality fish oils can even lower the mercury content to near undetectable levels (source: APA).

Because the amount of mercury in fish oil supplements is small or even undetectable, fish oil is safe for pregnant women.

Where the omega-3 oil is sourced from does matter when it comes to health benefits, but not safety.

Both marine algae and fish-derived omega-3 oils are safe to use when pregnant (source: World Health Organization). However, this article is focused specifically on omega-3 oils from fish.

One safety exception is oil derived from fish liver, often seen labeled as cod liver oil.

No matter which type of fish the oil comes from, oil made from fish livers is too high in vitamin A. This can be dangerous during pregnancy and fish liver oil is best avoided.

fish oil capsules

Can I Take Fish Oil in the First Trimester?

What foods are safe during the first trimester of pregnancy are different that later trimesters, since the baby is at a much more critical point for growth and development. Fish high in mercury makes the list of foods to avoid during the first trimester.

Luckily for pregnant mothers, this doesn’t recommendation doesn’t extend to fish oil, which has low mercury levels, and it is safe to take during all trimesters of pregnancy (source: APA).

Fish Oil Pregnancy Dosage: How Much Should I Take?

Knowing that fish oil is safe to take while pregnant, many women also question how much is safe.

  • The National Institutes of Health (NIH) recommend that pregnant women get 1.4 grams of omega-3 fatty acids daily, across all sources (source: NIH).
  • The APA breaks this down a little further and advises pregnant women consume 300 mg of their omega-3s as DHA (source: APA).

    (Looking for more information on DHA? I’ll explain below!)
  • The APA also recommends that pregnant women choose a supplement that provides a minimum of 300 mg of DHA.

Further on in this article, I’ve provided a list of some common fish oil brands as a guide.

What Are The Benefits of Fish Oil During Pregnancy?

Fish oil is well known for protecting your heart, including lowering blood pressure and cholesterol, as well decreasing pain from rheumatoid arthritis (source: Mayo Clinic, NIH).

During pregnancy, women are often advised to take a fish oil supplement, but it’s not to help their hearts.

While pregnant, women need more omega-3 fatty acids- which is the fat source found in fish oil.

Omega-3 fatty acids play a crucial role in brain, cognition, and vision development for your little one.

Some studies even suggest that mothers have less risk of preterm birth and other complications, including postpartum depression, when they get sufficient omega-3 fatty acids during their pregnancy (source: APA, Reviews in Obstetrics in Gynecology).

Because omega-3 fatty acids are associated with brain development and cognition, a common question from women is whether or not taking a fish oil supplement has an impact on the likelihood of the child being on the autism spectrum.

A 2014 study found no link, neither positive nor negative, between maternal fish oil supplementation and autism spectrum disorder (source: Journal of the American Medical Association).

fish oil capsules spelling omega 3

What’s the Best Recommended Fish Oil Supplement for Pregnancy?

With fish oil being such a popular supplement, there may seem to be an endless number of brands available.

While this popularity is helpful to find the product you need whether online or in stores, the sheer number of products available can be overwhelming.

As a rule of thumb, it’s always best to choose a supplement with a quality seal on the bottle.

This signifies the supplement was tested by a third party to ensure the label is as accurate as possible.

This is important because national governments don’t control dietary supplements. In the US, for example, supplements are NOT regulated for safety by the FDA (source: FDA).

It’s left to the manufacturers to be responsible and honest about what’s in their products. Fortunately, many reliable manufacturers also submit their products for third-party quality testing.

Fish Oils and Purity Standards

Below is a list of well-respected brands that have been tested and verified as pure by third-party quality control companies:

 National Science Foundation (NSF)United States Pharmacopeia (USP)International Fish Oil StandardsNot certified
Nature Made X  
Nature’s Bounty X  
Kirkland X  
Pure Alaska Omega X  
Swisse   X
Blackmores   X
Klean AthleteX   
Nordic NaturalsX   
Smarty PantsX   
Carlson  X 

Labels may also claim that the product is “purified,” which is a step in the processing to remove heavy metals and other toxic substances.

While this claim sounds enticing, only products that have a third party seal are verified to be pure fish oil.

Other label claims include “non-GMO”, “organic”, and “responsibly-sourced”. None of these claims affect how healthy the oil is, so choosing a fish oil supplement with one of these claims on the bottle is up to your personal preferences.

Omega 3 Vs DHA During Pregnancy: Is There A Difference?

Like I talked about above, omega-3 is a type of fatty acid. In the body, omega-3 fatty acids go on to become more specific types of fatty acids and antioxidants, depending on what the body needs most at that time.

The most commonly talked about are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

DHA is the specific fatty acid needed to develop the tissue covering the baby’s retina and brain, so it is crucial that mothers get adequate amounts of this nutrient throughout pregnancy (source: Reviews in Obstetrics and Gynecology).

timeline of omega 3 to DHA and EPA

To make DHA, omega-3s go through 7 different steps in the body, and the omega-3s actually become EPA before they are ever turned into DHA.

The long road from omega-3 to DHA means that there is a higher chance that the final destination for the omega-3 is EPA rather than DHA.

Unfortunately, there is no way to predict whether omega-3s will ever make it all the way to becoming DHA in the body.

Fish oil supplements are available as omega-3, DHA only, EPA only, and a combination of either 2 or all 3 of the fatty acid types.

To meet the higher needs for DHA and because of the unpredictable evolution of omega-3s once in the body, women are advised to choose a supplement with at least 300 mg of DHA while pregnant.

Is Cod Liver Oil Safe During Pregnancy?

Fish liver oil, often made specifically from cod, is a different product than oils simply labeled “fish oil.”

As I mentioned earlier, oils made from fish livers are high in vitamin A/retinol. During pregnancy, high levels of vitamin A can harm baby’s development and lead to unwanted birth defects (source: Nutrients).

Because of the high amount of vitamin A/retinol in cod liver oil, women who are pregnant should not take or consume cod liver oil in any form, including fermented cod liver oil, capsules, and liquid drops (source: NHS). 

Can Cod Liver Oil Help You To Conceive?

While it’s not safe to take cod liver oil while pregnant, does the oil have any benefits when it comes to getting pregnant?

Fish oils, in general, contain fat-soluble vitamins, such as the vitamin A present in cod liver oil.

Fat-soluble vitamins are necessary to keep the reproductive system healthy and produce adequate amounts of hormones. However, cod liver oil is not the only source.

Fish oil not made from livers are also rich sources of fat-soluble vitamins without posing a risk for vitamin A toxicity.

Because regular fish oil is lower in the potentially toxic vitamin A, it is a better choice over cod liver oil, especially for women who are trying to or may become pregnant.

cod liver oil capsules on a table

In conclusion, fish oil is a supplement recommended to many pregnant women for its omega-3 content, more specifically DHA which is important for fetal brain and eye development.

Beyond being necessary to help support the baby’s growth, fish oil may help prevent early labor and other complications. Women need more of these nutrients during pregnancy, and are advised to consume at least 300 mg of DHA daily.

Not all supplements are created equal, however, and women should take care to choose brands tested for quality, while avoiding oils made from fish livers, as these can be toxic.

All in all, fish oil is a healthy and safe addition to your health regimen, even while pregnant.


Wondering about supplements in pregnancy? You may also like:

This article has been reviewed and approved for publication in line with our editorial policy.

Samantha Broghammer, RD

Samantha Broghammer, RD is a Wisconsin-based registered dietitian and nutrition writer. In addition to contributing to Pregnancy Food Checker, she serves the mental health and wellness population as a clinical dietitian providing medical nutrition therapy to those of all ages, from toddlers through senior citizens.

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