Pregnant women can enjoy herring as part of the two six-ounce servings of low mercury cooked seafood they eat per week. Due to high levels of mercury, the FDA recommends a limit on the amount and kind of seafood pregnant women ingest to prevent harm to themselves and their baby. According to the American Pregnancy Association, herring is in the class of fish considered to have the lowest amount of mercury. Additionally, pregnant women should only eat herring if it is fully cooked. According to the FDA, pregnant women should not eat any raw or undercooked seafood and should cook fish to at least 145°F.