A good place to look at eating right using the different food groups is MyPlate.
Eat a variety of foods. You should try to make sure you are eating foods from all the food groups at each meal. The food groups are Grains (6-11 servings/day – eat more whole grains), Vegetables (2 ½ - 3 cups/day), Fruits (2-4 servings/day), Dairy (3-4 servings) and Proteins (3 servings/day). Don’t forget – half your plate should be fruits and vegetables. Limit extra calories from soda, sweets and fats to stay healthy. Some women find it easier and more enjoyable to eat four to six smaller more frequent meals during the day then three larger meals. Do what fits your lifestyle best and is most comfortable for you. Most women need an extra 300 calories per day during pregnancy. Check with your doctor about your calorie needs. Don’t forget to drink enough fluids. You should drink at least six to eight glasses of water in addition to milk and/or juice. Talk with your doctor about a prenatal vitamin/mineral supplement. Key nutrients include vitamin D, calcium, iron, and folic acid.
What about fish? You should include fish in your diet while pregnant. Fish is a great source of protein and iron. Many types of fish are rich in omega-3 fatty acids. Seafood is limited in pregnancy and lactation because methyl mercury accumulates in fish. Some fish have more mercury than others. You should avoid shark, swordfish, king mackerel and tilefish (blanquillo). Refrigerated smoked seafood should also be avoided. A good website for more information and specific limitations can be found here.
Are there any foods to avoid during pregnancy? You should avoid the fish listed above in addition to raw fish. You should also avoid drinking unpasteurized (raw) milk or juice. Guidelines also recommend avoiding foods made from unpasteurized milk like some cheese. Hot dogs and deli meats should be avoided due to the listeria bacteria. Alcohol should also be avoided during pregnancy. Talk with your doctor about caffeine intake and use of artificial sweeteners. For a more complete explanation and detailed lists of foods to avoid, look at ChooseMyPlate.gov.