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Seafood School | Astoria, Oregon | Health | Eating Fish During Pregnancy

Health: Eating Fish During Pregnancy

Straight Talk About Eating Fish During Pregnancy
By Joyce A. Nettleton, DSc, RD

A Dilemma
Here’s the dilemma - eating fish, especially oil-rich varieties such as salmon, trout, and sardines is good for you, especially during pregnancy. But fish may contain contaminants harmful to the developing fetus. Is it safe to eat fish during pregnancy and lactation?
The oils in fatty fish contain particular omega-3 fatty acids not found naturally in other foods. They are essential in pregnancy for the healthy development of brain, retina, and nervous tissue in the fetus and growing infant. Women must obtain omega-3s from foods because the body cannot make them from other fats. During pregnancy these fatty acids are transferred from the mother’s tissues to the fetus via the placenta. After birth, the infant’s brain and nervous system continues to develop and the infant obtains omega-3s from the mother’s milk.
However, eating fish requires special consideration for women in the childbearing years and for young children. While women need the omega-3s found in oil-rich fish during pregnancy and lactation, they must avoid possible contaminants, which can be passed on to the fetus and nursing infant. Fortunately, there are ways to minimize exposure to possible contaminants.

What is the Danger?
The main concern in pregnancy is to protect the fetus and young infant from exposure to environmental contaminants that can damage the infant’s developing brain and nervous system. Thus, it is important for pregnant and nursing women to be aware of the sources of these contaminants and minimize their consumption of foods that may contain them. The most important potential contaminants in seafood to avoid are mercury, PCBs, and pesticide residues, as these can accumulate in the body. These contaminants may be found in certain species of fish. Is there a way out of this bind?

The Good News
Some kinds of fish are safe and healthful to eat regularly. They are very low in contaminants and rich in omega-3s. These fish include all forms of salmon, rainbow trout, canned salmon, sardines, herring, and pilchard. Many other fish species such as sole, flounder, haddock, farmed catfish, farmed striped bass, farmed tilapia, and most shellfish are also low in contaminants, but these have much less omega-3s. Eating small amounts of omega-3s, however, is better than having none.

Which Fish Are Most Risky?
Because of their eating habits, some fish species are highly likely to be contaminated and should be avoided during pregnancy and lactation. Predator fish - those that eat other fish - and fish that live many years such as, swordfish, shark, marlin, and large tuna accumulate the most contaminants. Several kinds of freshwater sport fish throughout the U.S. are likely to be contaminated with PCBs, mercury, and other pollutants. The accumulation of contaminants depends on the type of fish, what it eats, the amount of pollution in its environment, and its age.
2Trimming and preparation methods do not reduce the amount of mercury in portions we eat because mercury is distributed throughout the fish. However, trimming and cooking can reduce PCBs and other residues because they are found mainly in the fat.

The Environmental Protection Agency (EPA) issues warnings about contaminants in freshwater fish and at least 40 states have issued fish consumption advisories related to contaminants. Popular sport fish, particularly large and small mouth bass, northern pike, walleye, pickerel, and lake whitefish often have high levels of mercury. Other sport fish, especially those from waters contaminated by toxic industrial wastes, can have high levels of pollutants. Because the likelihood of contamination depends on the particular body of water where the fish was caught and the fish species, it is important to check your state fish consumption advisory before eating any recreationally caught fish. For example, Florida advises everyone to avoid eating largemouth bass, bowfin, bluefish, and gar. Fish consumption advisories are available from your state’s Department of Natural Resources or Public Health.

Safest Advice for Pregnant and Nursing Women
During pregnancy and lactation, avoiding certain species entirely is the safest way for a woman to protect her unborn child from mercury and other contaminants. Is it ever safe to consume any of the most contaminated species and others with modest levels of contaminants? The answer is, “it all depends.” The greatest danger comes from eating highly contaminated fish regularly over a long time. A single meal, consumed only once in a while, is unlikely to be harmful. But the answer really depends on several factors. One is the amount of contaminants in the fish. Another is how often and how much contaminated fish one eats, and what a person’s background level of contamination might be. Contaminant levels are highly variable among different species of fish and even within a particular species. In general, the smaller and younger the fish, the less likely it is to have high contaminant levels. Fish that feed on plants and small organisms are less likely to be contaminated. Most of us do not have this kind of detailed information about fish. That is why the US Food and Drug Administration (FDA) and state governments give advice in terms of how much and how often it is safe for people, including pregnant women, to eat particular kinds of fish.

FDA’s Recommendations
The FDA warns pregnant and lactating women and young children to avoid eating swordfish, shark, king mackerel, and tilefish, also known as golden bass or golden snapper, because of their high mercury content. The Canadian government advises women of childbearing age and young children to limit shark, swordfish, and fresh or frozen tuna steaks to one meal a month. The British government advises its people to eat no more than one serving a week of shark, swordfish, and marlin.

The amount of mercury in fish that the FDA considers safe is controversial. Canada set its safe level at half the FDA level. The EPA and Japan set levels even lower. The FDA level is used by the European Commission and for international trade in predatory species such as shark and swordfish. For all other fish, however, the Food and Agriculture Organization of the United Nations set a level of half that of the FDA. Clearly, there is no agreement about safe mercury levels.

The Tuna Tussle
Probably the most controversial fish is tuna. That is because tuna, especially in canned form, is the most widely consumed fish in the U.S. Canned tuna tends to have lower contaminant levels than fresh and frozen forms, in part because different tuna species are used. Also, the amount of tuna people consume differs greatly. People eating more than two 6 ounce cans a week on a regular basis risk consuming more mercury than advisable. FDA has not warned against eating tuna in any form, as long as one eats no more than 12 ounces a week and no other fish besides. Twelve ounces is equivalent to two small cans of tuna a week. In July 2002, however, the FDA’s own Food Advisory Panel recommended that FDA advise women of childbearing age and young children to consume no more than one 6 ounce can of tuna a week. The FDA held its ground and is studying the issue.

Although data are limited, tuna species sold fresh for sashimi and steaks generally come from larger older fish that are more likely to have higher contaminant levels. That is why Canada includes fresh and frozen tuna steaks in its warning list. Canned white meat or albacore tuna also comes from larger fish. Albacore may have somewhat higher mercury levels than light or chunk tuna which comes from smaller skipjack and yellowfin tuna.
What about mercury in other species of fish? Because mercury is found in fish worldwide many fish have some detectable mercury. For most species mercury is substantially below the most stringent safety levels. As a result, eating different kinds of fish on a regular basis remains safe. A report in 2000 from the US National Academy of Sciences examined the dangers of mercury and concluded that the risk of harm from the current intake of mercury in the majority of people is low. The report recognized the many health benefits of eating fish and encouraged people to eat those fish known to have the lowest mercury levels (see Sidebar).

Other Safety Tips
Pregnant and lactating women and children should avoid eating all raw fish and shellfish. Raw seafood, especially raw shellfish, can carry parasites and harmful microorganisms that can cause serious illness. One should also avoid potentially toxic fish such as pufferfish (fugu), blowfish and sea squab. Parents with seafood allergies or other serious allergies such as bee stings and pollen should not feed shrimp, crab, crayfish, and lobster to their children under the age of three, who may be likely to develop these allergies.

The Bottom Line
Women can and should consume several species of fish rich in omega-3s on a regular basis without fearing toxicity from mercury and other contaminants. Many other fish and shellfish can be enjoyed without fear of contaminants. Fish and shellfish have high quality easily digested protein, and many have valuable amounts of vitamins and minerals. Many are very low in fat and the richer varieties have oils that protect and promote health. Seafood continues to deserve a priority on everyone’s weekly menu.

Side Bar
All women, including pregnant and nursing women, can safely consume these omega-3 rich fish twice a week:

Salmon in all forms, except from the Great Lakes
Farmed trout
Fish low in contaminants and with less omega-3s than the above:
Flounder and sole
Farmed catfish, striped bass, tilapia
Mahi mahi
Crab, shrimp, scallops, clams, oysters, mussels, crayfish
Note: Fish not listed are safe to consume at least once a month

Pregnant and nursing women and young children should avoid eating:
Raw fish and shellfish of any kind
King mackerel
Tilefish (golden bass, golden snapper)
Large and small mouth bass
Northern pike
Lake whitefish
Salmon from the Great Lakes
Toxic species such as pufferfish (fugu), blowfish and sea squab
All sport fish caught in states issuing a fish consumption advisory for that species

Article reprinted with permission from the author.
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