You want what's best for your baby, and that includes ensuring the healthiest pregnancy diet possible. But do you also know what foods to avoid? "Everything you eat and drink you share with your baby, so it makes sense to be extra careful about the foods and drinks you choose during this time," says Bridget Swinney, M.S., R.D., author of Eating Expectantly: A Practical and Tasty Guide to Prenatal Nutrition.

Here's a checklist of foods you should stay away from if you're expecting:

Large fish

Shark, swordfish, tilefish, and king mackerel all contain dangerously high levels of methyl mercury (a poison found in fresh and salt waters, no thanks to industrial pollution). At high levels, mercury can cause damage to the nervous system -- especially to children and unborn babies. Low amounts can also affect the central nervous system, creating things like learning deficits. Since mercury builds up in the body, it's also wise to stay away from these fish if you're planning to become pregnant or are nursing.

Soft cheeses

Because of the way these cheeses are made, they can contain a bacteria called Listeria which can cause miscarriage. Types to avoid include: Brie, camembert, roquefort, feta, and gorgonzola, as well as Mexican-style cheese like queso blanco and queso fresco.

Deli fare

Deli meats (such as ham, turkey, salami, and bologna) and cold salads (like tuna and egg) can also be contaminated with listeria. Swinney advises reheating meats in a microwave to steaming to help kill any potential bacteria, or skipping them altogether.

Undercooked eggs

Raw or undercooked eggs (such as poached, sunnyside up, and over-easy) don't reach high enough temperatures to kill off the harmful salmonella bacteria which can be found in egg yolk. A good rule of thumb is not to eat anything with a runny yolk. Alternatively, use egg substitutes, which are pasteurized. Also beware of souffles since they contain undercooked eggs, and traditional Caesar salad dressing made with raw eggs.

Raw or undercooked beef

To prevent the risk of E. coli bacteria poisoning or toxoplasmosis, which is harmful to a fetus, make sure meat reaches a temperature of 160 degrees. If you're ordering a burger out, ask for it be cooked well-done and check that there's no pink once it arrives; steaks are fine cooked to medium well (which means they may be a little pink in the center.)

Herbal teas

"We just don't know enough about the effects of herbs during pregnancy, so it makes sense to play it safe and stick with decaf black tea or flavored teas," says Swinney.