Seafood

While fish are a great source of protein and heart-healthy omega-3 fatty acids, some are also chock full of mercury, a metal that can harm the developing brain of a fetus. Swordfish, tilefish, king mackerel and shark are particularly high in mercury and should be avoided during pregnancy, according to the U.S. Department of Health and Human Services. Pass on sashimi and other uncooked seafood, including raw oysters, too, health officials say. In addition to putting you and your baby at risk of mercury exposure, they may contain parasites such as tapeworm, which can rob your baby of vital nutrients.