Pregnant women can enjoy clams as part of the six six-ounce servings of moderate mercury cooked seafood they eat per month. The FDA recommends a limit on the amount and kind of seafood pregnant women ingest to prevent harm to themselves and their baby caused by high levels of mercury. Clams are in the class of seafood considered to have a moderate amount of mercury according to the American Pregnancy Association. Additionally, pregnant women should only eat clams if they are fully cooked. According to the FDA, pregnant women should not eat any raw or undercooked seafood and should cook clams until the shells open. If the shells do not open, those clams should not be eaten.