The Food and Drug Administration and the Environmental Protection Agency advises pregnant women, nursing mothers and those who may become pregnant to limit their consumption of seafood to 12 ounces a week -- about two to three modest meals.
Consumers should mix the types of fish they eat and not to eat any one kind of fish or shellfish more than once a week, the government advises.
The FDA had previously warned pregnant women against eating shark, swordfish, king mackerel and tilefish because of high high levels of mercury.
Mercury levels in tuna vary, but tuna steaks and canned albacore tuna generally contain higher levels of mercury than canned light tuna, according to the advisory, "You can safely include tuna as part of your weekly fish consumption."
"It is implicit in the draft document that women at risk should eat no more than four to six ounces of tuna once a week," David Acheson, the FDA's medical officer, told the Washington Post.
Shrimp is the most popular seafood in America, followed by tuna.