Some foods may contain harmful germs or toxins. Certain infections, for example, toxoplasmosis and listeria, are particularly dangerous during pregnancy because they can pass through the placenta and infect the baby. Often the mother has few symptoms. Other illnesses like the toxic form of E. coli, Salmonella, and other types of food poisoning don't pose a specific risk to pregnant women, but can make anyone very ill; taking simple steps to prevent infection can save you from a bellyache -- or worse -- later.

• Rinse fresh fruits and vegetables in running tap water to remove visible dirt and grime.  Remove and discard the outermost leaves from lettuce or cabbage.
  
  
• Avoid any products made from unpasteurized milk, raw or partially cooked eggs, raw or undercooked meat and poultry, unpasteurized juices, and raw sprouts. Remember that eggnog and Caesar salad dressing are sometimes made with raw eggs. And don't taste that cookie dough until it is a cooked cookie! Pasteurized eggs are available if you really want that Caesar salad.
  
  
• Wash hands, utensils, and cutting boards after they have been in contact with raw meat or poultry and before they touch another food.  Put them through the dishwasher, or wash with 1 teaspoon of chlorine bleach diluted in 1 quart of water. Put cooked meat and poultry on a clean platter, rather than back on one that held the raw food, and switch to new utensils for serving. 
  
  
• Cook meat, poultry and eggs thoroughly.  Use a meat thermometer to be sure ground meat reaches an internal temperature of 160°, and steaks, 145°. To prevent salmonella infection, eggs should be cooked until the yolk is firm, or use pasteurized eggs. 
  
  
• Refrigerate perishable food promptly and defrost foods properly.
  
  
• Don't cause food poisoning yourself! Wash your hands with soap and water before preparing food. 
  
  

For more information check out the FDA's food safety website and my previous entry Foods to Avoid in Pregnancy: 8 Questions Answered.