When choosing a healthy diet, many expecting moms may wonder whether fish is a safe option. There are many types of fish that are considered safe for consumption and are recommended for pregnant and breastfeeding moms.  Fish is a great source of healthy fats, protein, and omega-3 fatty acids and can provide important nutrients for your baby’s growth and development. The Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) published a table containing different types of fish under the headings, “Best Choices,” “Good Choices,” and “Choices to Avoid,” to assist expecting moms in choosing the healthiest options. “Best Choices” have the lowest levels of mercury, and “Choices to Avoid” contain the highest levels. The FDA and EPA recommend that pregnant and breastfeeding moms consume 2 to 3 servings of fish every week from the “Best Choices” category or 1 serving per week from the “Good Choices” category. You can see what types of fish are recommended in the table on the FDA website. Among some of the “Best Choices” are popular options, such as canned light tuna, haddock, anchovy, shrimp, scallop, salmon, and tilapia. Expecting moms should strive to eat a variety of types of fish and avoid consuming the same type of fish repeatedly.
The FDA and EPA have identified 7 types of fish that should be avoided because they contain the highest mercury levels. These include bigeye tuna, marlin, shark, swordfish, orange roughly, king mackerel, and tilefish from the Gulf of Mexico. There is no way to reduce the mercury found in these 7 types of fish, so expecting moms should avoid these options altogether. The best way to reduce mercury exposure from fish consumption is to consume fish that are included on the “Best Choices” list.
You may notice that some types of fish can be included in the table in more than one category. It is important to consider the specific type of fish before deciding that it is safe to eat. For example, while canned light tuna (including skipjack) is safe to eat and is classified under “Best Choices,” bigeye tuna is not safe and should not be consumed by expecting moms. Yellowfin tuna falls in the middle under the “Good Choices.”
Why do fish contain mercury?
Mercury exists in the environment and collects in bodies of water, including lakes, streams, and oceans. In water, mercury is converted to methylmercury, which gets absorbed by fish. Unfortunately, fish can only eliminate limited amounts of methylmercury, causing this contaminant to accumulate in their muscles.  Almost all fish contain some methylmercury, but higher levels are found in fish that live longer because they absorb more methylmercury over time. Larger predatory fish that consume other fish also have higher amounts of mercury.
What are the risks of methylmercury to my baby?
Mercury passes through the placenta and exposes your baby to its harmful effects. High exposure to mercury can cause problems with your baby’s brain development and lead to impaired vision or hearing. [2,3] Consuming fish has been found to correspond to higher mercury concentrations in the hair and blood in pregnant women. However, it is unclear what types of fish these women consumed. If you are concerned about exposure to methylmercury, you can ask your doctor about getting a hair or blood test to determine your mercury levels.
In addition to mercury, fish can contain other contaminants. The FDA has tested commercial seafood for the presence of pesticides and industrial chemicals and has concluded that the levels of other contaminants in commercially available fish are typically not hazardous.
Expecting moms should use caution with any type of fish that is caught by friends or family members. Some of these types of locally caught fish, including perch, trout, catfish, and carp, can contain higher levels of mercury and other contaminants. These fish may not be safe for consumption during pregnancy. You can check fish advisories pertaining to the particular body of water where the fish was caught. Additionally, state and local health departments can provide more information about the types of contaminants that may be a risk where you live. If no information is available about the safety of the waters where the fish was caught, it is recommended to only consume one serving of that fish per week and consume no other sources of fish for that week.
What is a serving of fish?
One serving of fish is 4 ounces, which is about the size and thickness of the palm of your hand. 
What about raw fish?
Regardless of whether the type of fish is included in the “Best Choices” category, expecting moms should not consume raw fish. It is important to ensure that any fish you consume is cooked to a safe temperature to ensure that you and your baby are not exposed to harmful bacteria or other infectious organisms.
Replacing other types of meat with fish a few times per week is a great way to provide your growing baby with important nutrients. Be sure to use the table created by the FDA and EPA to determine which fish are safe to consume during pregnancy and while breastfeeding.
- U.S. Food & Drug Administration. United States Environmental Protection Agency. Eating Fish: What Pregnant Women and Parents Should Know.
- Koren G, Bend JR. Fish consumption in pregnancy and fetal risks of methylmercury toxicity.
- March of Dimes. Mercury and Pregnancy.