What to Know About Mercury While Pregnant or Breastfeeding

Pregnancy and breastfeeding come with enough mental tabs open already: prenatal vitamins, sleep positions, baby names, snack cravings, and the sudden urge to Google every ingredient in your lunch. Then mercury enters the chat, usually through warnings about fish. Should you eat seafood? Avoid tuna forever? Say goodbye to sushi until kindergarten graduation? Thankfully, the answer is not nearly as dramatic.

Mercury matters because too much exposure can affect a baby’s developing brain and nervous system. But seafood also provides protein, omega-3 fatty acids, iodine, iron, vitamin D, vitamin B12, and cholinenutrients that support pregnancy, breastfeeding, and infant development. The goal is not to panic or ban fish from your plate. The goal is to choose wisely, eat the right amount, and avoid the fish most likely to carry high mercury levels.

This guide breaks down what mercury is, why it matters during pregnancy and breastfeeding, which fish are safer, which fish to skip, and how to build a realistic seafood routine that does not require a marine biology degree.

What Is Mercury and Why Is It a Concern?

Mercury is a naturally occurring metal found in the environment. It can also be released through human activities such as burning coal, industrial processes, and waste disposal. Once mercury reaches lakes, rivers, and oceans, microorganisms can convert it into methylmercury, the form that builds up in fish and shellfish.

Methylmercury is the type most often discussed in pregnancy nutrition because it can accumulate in the body over time. Larger, older predator fish usually contain more mercury because they eat smaller fish and live long enough to collect more of it. Think of it as the seafood version of “you are what you eat,” except the shark has eaten half the buffet.

During pregnancy, mercury can pass through the placenta. During breastfeeding, smaller amounts can pass into breast milk. The developing brain and nervous system are especially sensitive, which is why pregnant and breastfeeding people are advised to limit high-mercury seafood while still eating lower-mercury options.

Should You Eat Fish During Pregnancy or Breastfeeding?

Yes, in most cases, you should eat fish while pregnant or breastfeedingjust choose lower-mercury fish. U.S. health guidance generally recommends 8 to 12 ounces of lower-mercury seafood per week for people who are pregnant, planning pregnancy, or breastfeeding. That equals about two to three adult servings weekly.

Fish is one of the best natural sources of DHA and EPA, two omega-3 fatty acids associated with brain and eye development. Seafood can also provide iodine, which supports thyroid function; choline, which plays a role in fetal brain development; and high-quality protein, which is basically the construction crew for growing and repairing body tissue.

The key phrase is “lower-mercury seafood.” Not all fish are created equal. Salmon and sardines are very different from swordfish and bigeye tuna when it comes to mercury exposure.

How Much Seafood Is Safe?

A helpful weekly target is:

• Eat 2 to 3 servings per week from the lower-mercury “best choices” category.
• One adult serving is about 4 ounces before cooking.
• Choose variety instead of eating the same fish every day.
• Limit “good choice” fish to about one serving per week.
• Avoid the highest-mercury fish completely during pregnancy and breastfeeding.

A practical example: You might have salmon for dinner on Monday, shrimp tacos on Wednesday, and a tuna salad made with canned light tuna on Friday. That is far more useful than trying to calculate mercury levels with a spreadsheet while standing in the grocery aisle.

Best Low-Mercury Fish During Pregnancy and Breastfeeding

Lower-mercury fish and shellfish are the easiest way to get seafood benefits while keeping mercury exposure low. Good options include:

• Salmon
• Sardines
• Anchovies
• Trout
• Atlantic mackerel
• Herring
• Pollock
• Cod
• Catfish
• Tilapia
• Shrimp
• Scallops
• Crab
• Clams
• Oysters, fully cooked
• Canned light tuna, including skipjack

These choices are popular for a reason: they are widely available, easy to cook, and usually budget-friendly. Salmon, sardines, trout, and anchovies are especially valuable because they are rich in omega-3s. Shrimp and tilapia are lower in omega-3s than salmon, but they still offer lean protein and can be part of a healthy rotation.

Fish to Avoid Because of High Mercury

Some fish are best left off the menu during pregnancy and breastfeeding because they tend to have the highest mercury levels. Avoid:

• Shark
• Swordfish
• King mackerel
• Marlin
• Orange roughy
• Tilefish from the Gulf of Mexico
• Bigeye tuna

These are generally large predatory fish. They may look impressive on a restaurant menu, but pregnancy is not the season for seafood roulette. Choose salmon over swordfish, canned light tuna over bigeye tuna, and trout over tilefish from the Gulf of Mexico.

What About Tuna?

Tuna is where many people get confused, and honestly, tuna has earned its reputation as the “it depends” fish. The type of tuna matters.

Canned Light Tuna

Canned light tuna, often made from skipjack, is generally considered a lower-mercury option. It can count toward your weekly 8 to 12 ounces of lower-mercury seafood.

Albacore or White Tuna

Albacore tuna, also called white tuna, has more mercury than canned light tuna. If you eat albacore, keep it limitedabout one serving per week is a common practical approach.

Bigeye Tuna

Bigeye tuna is high in mercury and should be avoided during pregnancy and breastfeeding. This is especially relevant when ordering sushi or tuna steaks, because menus do not always make the species obvious. When in doubt, ask.

Does Cooking Fish Remove Mercury?

No. Cooking fish does not remove mercury. Mercury builds up in fish muscle, not just in the skin or fat. That means trimming, draining, grilling, baking, steaming, or broiling will not meaningfully reduce mercury levels.

Cooking still matters for food safety. Pregnant people should avoid raw or undercooked seafood because of the risk of harmful bacteria, viruses, and parasites. Fish should generally be cooked until it reaches an internal temperature of 145°F, flakes easily, and appears opaque. Shellfish should be cooked thoroughly, and clams, mussels, and oysters that do not open after cooking should be discarded.

What About Sushi While Pregnant?

Sushi is not automatically a villain, but raw fish is usually not recommended during pregnancy because of foodborne illness risks. Cooked sushi rolls can be a safer option. For example, rolls made with cooked shrimp, cooked crab, cooked salmon, avocado, cucumber, or egg can satisfy the sushi craving without turning lunch into a medical mystery novel.

Also pay attention to mercury. A cooked roll made with low-mercury seafood is different from a raw bigeye tuna roll. If the restaurant cannot tell you what kind of tuna it uses, choose something else.

Local Fish: Check Advisories First

If you eat fish caught by family or friends from local lakes, rivers, ponds, or coastal waters, check your local fish advisory before eating it. Local advisories may warn about mercury, PCBs, or other contaminants.

If no advisory is available, a cautious approach is to eat only one serving of that local fish that week and avoid other fish during the same week. This is especially important for larger local fish such as certain trout, bass, carp, catfish, or perch, depending on the area.

Mercury Outside of Fish

Fish is the main dietary source of methylmercury, but mercury can also show up in other places. Older thermometers, fluorescent bulbs, some industrial workplaces, antiques, certain imported cosmetics, and dental settings may involve elemental mercury exposure.

An intact mercury thermometer or light bulb is not usually a problem. A broken one is different because mercury can spill and release vapor. Do not vacuum spilled mercury. Vacuuming can spread mercury vapor into the air, which is exactly the opposite of helpful. Follow local health department or environmental cleanup instructions, and ask someone who is not pregnant to handle the cleanup if possible.

If you work in dentistry, recycling, electrical manufacturing, mining, chemical processing, or another job where mercury exposure is possible, talk with your supervisor, safety officer, and health care provider. Workplace protections matter, and pregnancy is a good reason to review them carefully.

Dental Fillings and Pregnancy

Dental amalgam fillings contain mercury, along with other metals. If you already have amalgam fillings and they are intact, they are not usually removed just because you are pregnant. In fact, removing a stable filling unnecessarily may increase short-term exposure. If a filling is damaged, painful, or needs replacement, tell your dentist you are pregnant or breastfeeding so the safest plan can be made.

Do not skip urgent dental care during pregnancy. Infections and untreated dental problems can create their own risks. The smart move is communication: tell your dentist, tell your prenatal care provider, and make decisions based on your actual dental situation rather than internet panic.

Simple Meal Ideas With Lower-Mercury Seafood

Eating fish does not have to mean elaborate recipes or a kitchen that smells like a harbor. Try these easy meal ideas:

• Salmon with roasted sweet potatoes and green beans
• Shrimp tacos with cabbage slaw and avocado
• Whole-grain pasta with canned salmon, lemon, and peas
• Trout with brown rice and steamed broccoli
• Canned light tuna on whole-grain toast with cucumber slices
• Sardines on crackers with tomato and a squeeze of lemon
• Cod baked with olive oil, garlic, and herbs

If nausea makes fish smell impossible during pregnancy, you are not failing nutrition. Try milder options like cod, tilapia, shrimp, or canned light tuna served cold. You can also get omega-3s from DHA-fortified foods or prenatal supplements, but talk with your health care provider before adding supplements.

Breastfeeding and Mercury: What Changes After Birth?

The same general seafood advice continues while breastfeeding. Mercury can pass into breast milk in small amounts, but breastfeeding has major benefits, and the answer is not to stop breastfeeding because you ate fish. The answer is to choose lower-mercury seafood and avoid the highest-mercury fish.

Breastfeeding parents need steady nutrition, hydration, and enough calories to support milk production and recovery. Lower-mercury seafood can fit beautifully into that picture. A salmon rice bowl, shrimp soup, or tuna sandwich made with canned light tuna can be practical, nourishing, and fastthree qualities that matter when a baby believes sleep is a rumor.

Common Mistakes to Avoid

Avoiding All Fish

Many people hear “mercury” and stop eating seafood completely. That can mean missing out on nutrients that support fetal and infant development. A better approach is selective eating: skip high-mercury fish and include lower-mercury choices.

Eating the Same Fish Too Often

Variety helps reduce the chance of overdoing any one contaminant and improves nutrient diversity. Rotate salmon, shrimp, cod, sardines, trout, canned light tuna, and other lower-mercury options.

Assuming Expensive Means Safer

Price does not equal low mercury. Swordfish can be expensive and still be a poor pregnancy choice. Meanwhile, humble canned light tuna or sardines can be convenient, affordable, and lower in mercury.

Forgetting Local Fish Advisories

Fish caught from local waters may have different safety concerns than store-bought seafood. Always check advisories before eating locally caught fish while pregnant or breastfeeding.

Experience-Based Tips: Real-Life Lessons From Pregnancy and Breastfeeding

One of the biggest real-life lessons about mercury while pregnant or breastfeeding is that people rarely need more fear; they need clearer decisions. Imagine a pregnant parent standing in the grocery store, holding a can of tuna in one hand and a package of salmon in the other, wondering whether dinner is about to become a science experiment. The practical solution is simple: choose canned light tuna instead of albacore most of the time, rotate it with salmon or shrimp, and keep total lower-mercury seafood around two to three servings per week.

Another common experience is the restaurant moment. A server says, “Our special tonight is swordfish,” and it sounds elegant, buttery, and very adult. During pregnancy, that is the moment to smile politely and order the salmon. No speech required. No dramatic table announcement. Just a quiet, confident swap.

Breastfeeding brings a different challenge: convenience. New parents often eat whatever can be held in one hand while the baby is held in the other. That is where safe seafood planning helps. Keeping packets of salmon, canned light tuna, frozen shrimp, or cooked fish leftovers in the refrigerator can make nourishing meals easier. A quick bowl with rice, canned salmon, avocado, and steamed vegetables can feel like a tiny victory on a very tired day.

Some people also deal with family advice that is outdated or contradictory. One relative may say, “Eat fish every day; it makes the baby smart.” Another may say, “Never touch seafood until the baby is born.” The balanced answer sits in the middle: eat seafood, but choose lower-mercury options and avoid the high-mercury list. Pregnancy nutrition is not a contest in extremes.

There is also the emotional experience of making one “wrong” choice. Maybe someone ate a tuna steak before realizing it might have been high in mercury. One meal is not usually a reason to panic. Mercury concern is mostly about repeated exposure over time. The best next step is to avoid high-mercury fish going forward and discuss concerns with a health care provider, especially if exposure was frequent.

Finally, many parents find that writing down a short “safe seafood list” reduces stress. Put salmon, sardines, shrimp, cod, tilapia, trout, pollock, catfish, scallops, crab, and canned light tuna on the yes list. Put shark, swordfish, king mackerel, marlin, orange roughy, Gulf tilefish, and bigeye tuna on the no list. Tape it inside a cabinet or save it on your phone. When your brain is busy growing or feeding a human, fewer decisions are a beautiful gift.

Conclusion

Mercury is important to understand during pregnancy and breastfeeding, but it does not mean seafood has to disappear from your life. The healthiest approach is balanced: eat 8 to 12 ounces per week of lower-mercury fish, choose a variety of seafood, avoid high-mercury predators, cook seafood properly, and check local fish advisories when eating fish caught by friends or family.

Lower-mercury seafood can support your baby’s brain and nervous system development while also helping you meet your own needs for protein, omega-3s, iodine, choline, and other nutrients. With a few smart habits, you can enjoy fish without turning every meal into a detective case.

Medical note: This article is educational and should not replace advice from your obstetrician, pediatrician, midwife, lactation consultant, dentist, or other health care professional. If you have had a known mercury exposure, eat high-mercury fish often, or have concerns about your diet, ask your clinician for individualized guidance.