Pregnant women are urged to eat fatty fish regularly because it's the primary source of omega fatty acids, which are important for the baby's brain development. Despite the fact that a lot of the seafood we buy nowadays are tainted by mercury, experts say that the health benefits of fish consumption still outweigh the risks of mercury poisoning.

Still, by informing yourself of what sorts of fish are generally safer choices, you can reduce your exposure to mercury.

Another way to stay on the safe side is to keep track of the amount and type of fish you consume, and estimate your mercury exposure. This calculator is based on the data on mercury levels in commercial fish and shellfish, published by the FDA. The important thing is to keep below the EPA reference dose (RfD), defined as the amount of mercury a person, including sensitive subpopulations, can be exposed to on a daily basis over a lifetime without appreciable risk of effects.

Also, take note of this warning from the FDA:

Pregnant women, nursing mothers, women who might become pregnant, and children should not eat Swordfish, shark, tilefish, and king mackerel because of their high methylmercury content. The FDA also warns women and children to limit their consumption of tuna.