Mercury warnings are one of the first things people hear when they get pregnant. So it's natural to wonder whether fish oil carries the same risk as eating fish. Here's what the evidence says.
Written by Vita Globe Editorial Team | Reviewed against FDA/EPA advice, NIH guidance and peer-reviewed research
Is fish oil safe in pregnancy if you're worried about mercury?
Mercury is mainly a concern with certain fish, not purified fish oil. The NIH says omega-3 supplements haven't been found to contain mercury because it's removed during processing and purification[2]. A lab study of five fish oil brands found mercury ranging from undetectable to negligible[3]. For whole fish, the FDA and EPA advise 8 to 12 ounces a week of lower-mercury choices[1].
Caveat: That study was small and older, and supplement quality varies. Choose products with third-party testing and check any supplement with your OB or midwife.
Sources: NIH ODS (omega-3) · Foran 2003 · FDA/EPA fish advice · Verified 2026-09-27
In this article
Why is mercury a concern in pregnancy?
Some fish carry much more mercury than others. The concern in pregnancy and early life is the baby's developing nervous system. CDC notes that mercury can also pass into breast milk and affect an infant's neurodevelopment[4].
That's why the FDA and EPA publish specific advice for people who might become or are pregnant or breastfeeding, rather than simply telling them to avoid fish[1].
Which fish should you avoid while pregnant?
The FDA/EPA advice sorts fish into three groups. The "Choices to Avoid" list, which has the highest mercury levels, is short[1]:
- King mackerel
- Marlin
- Orange roughy
- Shark
- Swordfish
- Tilefish (Gulf of Mexico)
- Bigeye tuna
For fish you or family members catch, check local advisories. If there isn't one, the FDA suggests eating just one serving that week and no other fish[1].
Is fish oil safer than eating fish?
From a mercury standpoint, purified fish oil appears to be very low risk. The NIH notes that omega-3 supplements have not been found to contain mercury, since it's removed during processing and purification[2].
An often-cited lab study measured mercury in five over-the-counter fish oil products. Levels ranged from not detectable to negligible, similar to the background levels normally found in human blood. The authors concluded these products gave far less mercury exposure than eating high-mercury fish like swordfish or shark[3].
That doesn't make fish oil "better" than fish. Whole fish also provides protein and other nutrients. It just means that if you're avoiding fish over mercury worries, a purified supplement is a reasonable way to get omega-3s.
The honest summary
- Mercury is a real concern with a short list of fish[1].
- Purified fish oil supplements have tested very low for mercury[2][3].
- Low-mercury fish is still encouraged in pregnancy[1].
- Talk with your provider about the right mix for you.
Should you skip fish entirely to be safe?
No, and that's the part that often gets lost. The FDA and EPA actively encourage 8 to 12 ounces a week of lower-mercury seafood during pregnancy, or two to three 4-ounce servings from the Best Choices list[1]. Best Choices include salmon, sardines, anchovies, cod, shrimp, tilapia, trout and canned light tuna[1].
Omega-3 supplements have been linked to a lower risk of preterm birth in pooled trials[6], and fish is the main food source of those fats. Avoiding fish entirely, without replacing those omega-3s, may mean missing out. For meal ideas, see Omega-3 Foods to Eat During Pregnancy.
How to choose a fish oil supplement in pregnancy
- Look for third-party testing for purity and label accuracy.
- Check the DHA amount, not just total fish oil. See DHA vs. EPA.
- Be careful with cod liver oil. It also provides vitamins A and D[2], which adds to what's in your prenatal. Ask your provider first.
- Mention blood thinners. Fish oil may affect clotting times with warfarin[2].
- Expect mild side effects at most, like a fishy taste or heartburn[5].
Our option
Vita Globe Prenatal Fish Oil Gummies
Our Prenatal Fish Oil Gummies pair omega fatty acids from fish oil with vitamins that include folic acid (vitamin B9), in a raspberry and lemon chewable gummy. Suggested use is 2 gummies once daily; they're gluten-free, non-GMO and made without artificial colors or flavors. Every Vita Globe product is tested by an independent third-party lab. The exact DHA, EPA and folic acid amounts are on the Supplement Facts panel on the product page, so bring it to your OB or midwife. It contains fish, and it isn't a substitute for a prenatal vitamin your provider has recommended.
Frequently asked questions
Is canned tuna safe in pregnancy?
Canned light tuna is a Best Choice. Albacore (white) tuna is a Good Choice, so limit it to one serving a week[1].
Is salmon high in mercury?
No. Salmon is on the FDA/EPA Best Choices list[1].
Do fish oil supplements contain mercury?
The NIH says omega-3 supplements haven't been found to contain mercury because it's removed during processing[2].
Is sushi safe during pregnancy?
Mercury depends on the fish, but raw fish raises separate food safety concerns. Ask your provider about raw or undercooked seafood.
How much fish is too much in pregnancy?
FDA/EPA advice is 8 to 12 ounces a week from lower-mercury choices[1].
Sources
- U.S. Food and Drug Administration and U.S. Environmental Protection Agency. Advice about Eating Fish: For Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1–11 Years. Updated March 5, 2024. fda.gov
- NIH Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. Updated September 20, 2026. ods.od.nih.gov
- Foran SE, Flood JG, Lewandrowski KB. Measurement of mercury levels in concentrated over-the-counter fish oil preparations: is fish oil healthier than fish? Arch Pathol Lab Med. 2003;127(12):1603-1605. doi:10.5858/2003-127-1603-MOMLIC
- Centers for Disease Control and Prevention. Maternal Diet and Breastfeeding. Updated August 25, 2026. cdc.gov
- National Center for Complementary and Integrative Health. Omega-3 Supplements: What You Need To Know. Updated November 2024. nccih.nih.gov
- Middleton P, Gomersall JC, Gould JF, Shepherd E, Olsen SF, Makrides M. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev. 2018;11:CD003402. doi:10.1002/14651858.CD003402.pub3
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
